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 A236692 #19 Aug 08 2025 09:10:31
%S A236692 1,2,6,36,156,210,270,306,576,690,936,966,2136,2310,2550,2706,2850,
%T A236692 3390,3966,4026,4176,4260,4566,4590,5226,5430,5850,6120,6216,6360,
%U A236692 6420,6546,7410,7536,8940,9126,9240,9276,9900,10530,10836,11286,11586,11886,12390,13680
%N A236692 Numbers k such that k+1, 2*k+1 and k^2+1 are primes.
%C A236692 Intersection of A070689 and {b(n)=A005382(n)-1}.
%H A236692 Harvey P. Dale, <a href="/A236692/b236692.txt">Table of n, a(n) for n = 1..1000</a>
%t A236692 Select[Range[14000],AllTrue[{#+1,2#+1,#^2+1},PrimeQ]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Dec 27 2019 *)
%o A236692 (Python)
%o A236692 import sympy
%o A236692 from sympy import isprime
%o A236692 for n in range(100000):
%o A236692 if isprime(n+1) and isprime(n*2+1) and isprime(n*n+1): print(n, end=', ')
%o A236692 (PARI) isok(n) = isprime(n+1)&&isprime(2*n+1)&&isprime(n^2+1); \\ _Colin Barker_, Jan 30 2014
%Y A236692 Cf. A005382, A070689.
%K A236692 nonn
%O A236692 1,2
%A A236692 _Alex Ratushnyak_, Jan 30 2014