|
%I #14 May 02 2024 04:23:22
%S 0,1,2,3,4,6,8,10,14,36,41,213,229,555,569,2295,3108,5944,7370,17615,
%T 45894,141853,154773,184150
%N Numbers k such that (14*10^k + 37)/3 is prime.
%C For k > 1, numbers k such that the digit 4 followed by k-2 occurrences of the digit 6 followed by the digits 79 is prime (see Example section).
%C a(25) > 2*10^5.
%H Makoto Kamada, <a href="https://stdkmd.net/nrr">Factorization of near-repdigit-related numbers</a>.
%H Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/prime_difficulty.txt">Search for 46w79</a>.
%e 2 is in this sequence because (14*10^2 + 37)/3 = 479 is prime.
%e Initial terms and associated primes:
%e a(1) = 0, 17;
%e a(2) = 1, 59;
%e a(3) = 2, 479;
%e a(4) = 3, 4679;
%e a(5) = 4, 46679; etc.
%t Select[Range[0, 100000], PrimeQ[(14*10^# + 37)/3] &]
%o (PARI) isok(k) = isprime((14*10^k + 37)/3); \\ _Michel Marcus_, Dec 30 2017
%Y Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
%K nonn,more,hard
%O 1,3
%A _Robert Price_, Dec 29 2017
%E a(22)-a(24) from _Robert Price_, Dec 05 2018
|
