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%I #17 Jun 09 2021 11:13:16
%S 2,4,5,8,9,15,16,23,27,32,34,35,38,40,46,54,57,83,87,97,162,165,223,
%T 235,282,488,503,575,673,823,857,885,965,1112,1401,2288,2569,2788,
%U 3133,3539,4070,4654,5020,5613,6720,7773,11256
%N Integers k such that 3*k!!! + 1 is prime where k!!! is A007661(k).
%C Corresponding primes are 7, 13, 31, 241, 487, 87481, 174721, 289027201, 21427701121, ...
%e 4 is a term because 3*4!!! + 1 = 13 is prime.
%o (PARI) is(k) = ispseudoprime(3*prod(i=0, (k-2)\3, k-3*i) + 1); \\ _Jinyuan Wang_, Jun 09 2021
%Y Cf. A007661, A037083, A084438, A217647, A215779, A271396.
%K nonn,more
%O 1,1
%A _Altug Alkan_, Apr 06 2016
%E a(47) from _Jinyuan Wang_, Jun 09 2021
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