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 A129545 #21 Feb 22 2022 19:27:31 %S A129545 1,6,10,28,36,66,78,136,190,210,276,378,630,820,946,990,1128,1326, %T A129545 1596,1830,2016,2080,2346,2556,2850,2926,3570,3916,4560,4656,4950, %U A129545 5050,5778,6216,6328,8646,8778,9180,9870,11026,12720,13366,14028,14196,14878 %N A129545 Triangular numbers T such that T+1 is a prime. %C A129545 The only triangular numbers T such that T-1 is a (positive) prime are 3 and 6. %H A129545 Harvey P. Dale, <a href="/A129545/b129545.txt">Table of n, a(n) for n = 1..10000</a> %F A129545 a(n) = A000217(A067186(n)). - _R. J. Mathar_, Dec 10 2007 %F A129545 a(n) = A055469(n) - 1. - _Joerg Arndt_, Jun 19 2021 %t A129545 Select[Accumulate[Range[200]],PrimeQ[#+1]&] (* _Harvey P. Dale_, Nov 08 2011 *) %o A129545 (Python) %o A129545 from sympy import isprime %o A129545 def T(n): return n*(n+1)//2 %o A129545 def ok(T): return isprime(T+1) %o A129545 print(list(filter(ok, (T(n) for n in range(175))))) # _Michael S. Branicky_, Jun 18 2021 %Y A129545 Cf. A000217, A055469, A129755, A130178, A345350. %K A129545 nonn,easy %O A129545 1,2 %A A129545 _Zak Seidov_, May 30 2007