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 A166119 #8 Sep 18 2024 14:17:50
%S A166119 3,10,23,25,213,270,455,688,1060,1953,2233,2915,3468,3838,4718,4945,
%T A166119 8645,10230,11638,12308,13090,15428,16250,19295,23095,27778,29435,
%U A166119 32230,33488,43053,50830,71668,83485,86460,89365,96330,104610,106600,127823
%N A166119 a(n) = A165966(n)/12.
%C A166119 The only known primes in the sequence are 3, 23.
%F A166119 a(n) = (A086816(n) + 1)/6. - _Alois P. Heinz_, Sep 18 2024
%o A166119 (PARI) lista(nn) = {for (n = 1, nn, trg = n*(n+1)/2; if (!(trg % 2) && isprime(trg/2-1) && isprime(trg/2+1), print1(trg/12, ", ")););} \\ _Michel Marcus_, Oct 16 2013
%Y A166119 Cf. A000217, A001359, A086816, A105174, A111163, A165966.
%K A166119 nonn
%O A166119 1,1
%A A166119 _Zak Seidov_, Oct 07 2009