cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A126896 Numbers k such that 10*k! + 1 is prime.

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%I A126896 #30 Apr 16 2025 04:58:37
%S A126896 0,1,3,4,5,23,32,39,61,349,718,805,1025,1194,1550,1774,3417,7583
%N A126896 Numbers k such that 10*k! + 1 is prime.
%C A126896 a(17) > 2880. - _Jinyuan Wang_, Feb 05 2020
%C A126896 a(19) > 12000. - _Michael S. Branicky_, Jul 07 2024
%e A126896 k = 4 is a term because 10*4! + 1 = 241 is prime.
%o A126896 (PARI) is(k) = ispseudoprime(10*k!+1); \\ _Jinyuan Wang_, Feb 05 2020
%Y A126896 Corresponding primes are in A089764.
%Y A126896 Cf. A002981, A051915, A076679, A076680, A076681, A076682, A076683, A178488, A180626.
%K A126896 nonn,more
%O A126896 1,3
%A A126896 _Parthasarathy Nambi_, May 07 2007
%E A126896 a(15)-a(16) from _Jinyuan Wang_, Feb 05 2020
%E A126896 a(17) from _Michael S. Branicky_, Apr 16 2023
%E A126896 a(18) from _Michael S. Branicky_, Jul 07 2024