Jackpot numbers

 

Write vertically a number (like 419) and try to win the jackpot (using the hereunder martingale):

4 – a – d – g – j - m
1 – b - e – h – k - ...
9 – c – f – i – l - ...

1) compute the terms a, b, c, d, e… in the order shown above;
2) the sequence a, b, c, d, e… is always extended with the smallest prime not occurring before, such that…
3) … in each row, the first (yellow) digit of the next term is the rightmost digit of the preceding term;
4) a jackpot is won when all terms in a column have the same rightmost (blue) digit.

4 - 41 - 13 - 3  - 31 - 101 - 103 - 307 - 709
1 - 11 - 17 - 71 - 19 - 907 - 701 - 107 - 719
9 - 97 – 7  - 73 - 37 – 79  - 911 - 109 - 919 = jackpot!

Indeed, we have the same digit (9) ending all the terms of the last column.
And it takes 8 steps to win the jackpot with 419.

We can compute the number of such winning steps for any integer k > 9 (and start accordingly a sequence S):

10 => -1 (no number that contains a digit 0 can win a jackpot; we assign -1 to 10 to mark this impossibility – see the two rows generated by 10 hereunder):
   1 - 11
   0 - ? (no prime starts with 0)
11 => 6
   1 - 11 - 17 - 7  - 71 - 101 - 103
   1 - 13 - 3  - 31 - 19 - 97  - 73
12 => 2
   1 - 11 - 13
   2 - 2  - 23
13 => 3
   1 - 11 - 13 - 37
   33  - 31 - 17
14 => 1
   1 - 11
   4 - 41
15 => 2
   1 - 11 - 13
   5 - 5  - 53
16 => 1
   1 - 11
   6 - 61
17 => 10
   111 – 13 – 3  - 31 – 19 – 97 - 
701 – 101 – 103 - 307
   77  - 71 – 17 – 73 – 37 – 79 – 
907 – 709 – 911 – 107
18 => 2
   1 - 11 - 13
   8 - 83 - 3
19 => 6
   1 - 11 – 13 – 3  - 31 – 19 - 907
   9 - 97 – 7  - 71 – 17 – 73 – 37
20 => -1
21 => 2
   22  - 23
   111 - 13
...
100 to 110 => -1
111 => 5
1 - 11 – 19 – 97 – 73  - 37
1 - 13 – 3  - 31 – 101 – 107
1 - 17 – 7  - 71 – 103 - 307
112 => 8
1 - 11 – 17 – 
7  - 71 – 
101 – 103 – 311 - 109
1 - 13 – 3  - 31 – 19 – 97  - 79  - 907 - 709 
22  23 - 37 – 73 - 307 – 701 – 107 – 719
...
125 => 2
1 - 11 - 13
2 - 2  - 23
5 - 5  - 53
...
Etc.
 
I guess the sequence S of “winning steps” starts like that (thank you Carole!):

S = -1, 6, 2, 3, 1, 2, 1, 10, 2, 6, -1, 2, 6, 17, 3, 2, 3, 5, 2, 4, -1, 3, 17, 16, 2, 17, 2, 2, 1, 3, -1, 1, 3, 2, 4, 3, 1, 2, 4, 8, -1, 2, 2, 17, 3, 6, 3, 5, 2, 4, -1, 1, 3, 2, 1, 3, 11, 2, 4, 8, -1, 10, 5, 2, 2, 5, 2, 3, 3, 1, -1, 2, 2, 1, 4, 2, 4, 3, 4, 3, -1, 6, 4, 3, 8, 4, 8, 1, 3, 1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 5, 8, 19, 34, 8, 34, 6, 11, 8, -1, 8, 37, 3, 20, 2, 20, 50, 2, 9, -1, 19, 3, 26, 11, 3, 11, 28, 3, 36, -1, 34, 20, 11, 8, 20, 1, 73, 8, 8, -1, 8, 2, 3, 20, 37, 20, 50, 2, 9, -1, 34, 20, 11, 1, 20, 19, 73, 8, 8, -1, 6, 50, 28, 73, 50, 73, 17, 5, 123, -1, 11, 2, 3, 8, 2, 8, 5, 9, 55, -1, 8, 9, 36, 8, 9, 8, 123, 55, 12, ...
 
Another sequence (T) would be "Smallest integers needing n steps to win a jackpot"; I guess T would start like this:

T = 14, 12, 13, 29, 27, 11, ...
n =  1   2   3   4   5   6  ...
(no n = 7 yet in the first 190 terms of S)

P.-S.
Carole and a friend of mine say that S could start with nine 1s, provided you accept the result 1 for 0 < k < 10. We would then have for S':

S' = 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, 6, 2, 3, 1, 2, 1, 10, 2, 6, -1, 2, 6, 17, 3, 2, 3, 5, 2, 4, -1, 3, 17, 16, 2, 17, 2, 2, 1, 3, -1, 1, 3, 2, 4, 3, 1, 2, 4, 8, -1, 2, 2, 17, 3, 6, 3, 5, 2, 4, -1, 1, 3, 2, 1, 3, 11, 2, 4, 8, -1, 10, 5, 2, 2, 5, 2, 3, 3, 1, -1, 2, 2, 1, 4, 2, 4, 3, 4, 3, -1, 6, 4, 3, 8, 4, 8, 1, 3, 1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 5, 8, 19, 34, 8, 34, 6, 11, 8, -1, 8, 37, 3, 20, 2, 20, 50, 2, 9, -1, 19, 3, 26, 11, 3, 11, 28, 3, 36, -1, 34, 20, 11, 8, 20, 1, 73, 8, 8, -1, 8, 2, 3, 20, 37, 20, 50, 2, 9, -1, 34, 20, 11, 1, 20, 19, 73, 8, 8, -1, 6, 50, 28, 73, 50, 73, 17, 5, 123, -1, 11, 2, 3, 8, 2, 8, 5, 9, 55, -1, 8, 9, 36, 8, 9, 8, 123, 55, 12, ...

... and for T':

T' = 1, 12, 13, 29, 27, 11, ...
n =  1   2   3   4   5   6  ...
What do you think? S or S'? T or T'?
What would T'(7) be?



 

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  1. Ce commentaire a été supprimé par l'auteur.

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    1. yes, I think one should let S(n) = 1 when n < 10 is not a prime (for the one iteration to reach the jackpot : all terms (here just 1) are primes ending in the same digit).
      but maybe S(n) = 0 when n < 10 is a prime, because then we have this jackpot already at the beginning. For a(k) = smallest n which has S(n) = k, I get your values T'(1..6) and
      a(7) = 235, (which you didn't list above)
      a(8) = 49,
      a(9) = 129,
      a(10) = 17,
      a(11) = 66,
      a(12) = 199,
      a(13) = 239,
      a(14) = 225,
      a(15) = 227,
      a(16) = 33,
      a(17) = 23,
      a(18) = ??? (must be very large, > 10^6 I think !),
      a(19) = 113,
      a(20) = 124, ...

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