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 A305738 #15 Jun 25 2018 09:32:50
%S A305738 2,4,28,34,47,62,228,256,258,341,848,1362,1709,2262,2692,7907,10396,
%T A305738 10501
%N A305738 Numbers k such that k!*T(k) - 1 is prime, where T(k) is the k-th triangular number.
%C A305738 The PFGW program has been used to certify all the terms up to a(18), using a deterministic test which exploits the factorization of a(n) + 1. - _Giovanni Resta_, Jun 24 2018
%H A305738 Maheswara Rao Valluri, <a href="https://arxiv.org/abs/1803.11461">Primes of the form p = 1 + n! Sum n, for some n ∈ N*</a>, arXiv:1803.11461 [math.GM], 2018.
%t A305738 Do[If[ PrimeQ[n(n +1)!/2 - 1], Print@ n], {n, 3000}]
%o A305738 (PARI) isok(n) = ispseudoprime(n(n+1)!/ 2 - 1);
%Y A305738 Cf. A302859, A301373.
%K A305738 nonn,more
%O A305738 1,1
%A A305738 _Maheswara Rao Valluri_, Jun 22 2018
%E A305738 a(16)-a(18) from _Giovanni Resta_, Jun 24 2018