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 A174165 #3 Mar 30 2012 18:52:39 %S A174165 1,2,3,4,5,7,12,13,19,31,32,36,37,42,47,53,54,55,58,60,63,78,79,82,83, %T A174165 91,94,102,105,106,118,125,126,133,135,144,155,156,159,161,163,178, %U A174165 184,190,206,210,214,216,219,247,248,284,286,288,307,313,315,322 %N A174165 Numbers n for which (prime(n) - 1)^2 +1 is prime. %e A174165 a(1) = 1 because (1st prime -1)^2 +1 = (2-1)^2 +1 = 2, a prime; a(2) = 2 because (2nd prime -1)^2 +1 = (3-1)^2 +1 = 5, a prime; a(3) = 3 because (3rd prime -1)^2 +1 = (5-1)^2 +1 = 17, a prime; ... ; a(6) # 6 since (6th prime -1)^2 = (13-1)^2 +1 = 145 = 5*29, which is not a prime; etc. %t A174165 fQ[n_] := PrimeQ[ (Prime@n - 1)^2 + 1]; Select[ Range@ 335, fQ@# &] %Y A174165 Cf. A000040, A006093, A005722 & A127435. %K A174165 nonn %O A174165 1,2 %A A174165 _Juri-Stepan Gerasimov_, Mar 10 2010 %E A174165 Edited, corrected and extended by _Robert G. Wilson v_, Mar 14 2010