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.
%I A157833 #14 Aug 30 2024 09:46:12
%S A157833 2,3,5,7,15,19,41,59,61,105,661,2653,3069,3943,4053,8275
%N A157833 Numbers k such that 1 + Sum_{j=0..k} (-1)^j*(k-j)! is prime.
%C A157833 Note that when k is even, 3 divides the sum.
%C A157833 The sums corresponding to terms >= 661 are only probable primes. - _Klaus Brockhaus_, Mar 13 2009
%e A157833 a(2) = ((-1)^0)(2-0)! + ((-1)^1)(2-1)! + ((-1)^2)(2-2)! + 1 = 2! - 1! + 0! + 1 = 3 (prime).
%K A157833 nonn,more
%O A157833 1,1
%A A157833 _Kyle D. Balliet_, Mar 07 2009
%E A157833 a(7)-a(15) from _Klaus Brockhaus_, Mar 13 2009
%E A157833 a(16) from _Michael S. Branicky_, Aug 30 2024