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 A325439 #13 May 30 2019 01:16:02 %S A325439 3,4,6,7,9,10,11,13,14,15,16,17,19,21,23,24,26,27,29,32,34,35,36,38, %T A325439 40,43,45,48,50,51,52,55,56,57,59,62,64,65,66,68,70,71,72,73,75,76,77, %U A325439 78,79,80,81,82,83,85,87,89,90,91,95,97,98,99,101,103,107 %N A325439 Indices of primes of the form k^2 + 1 ending in 7. %C A325439 This sequence is presumably infinite. See 1st comment of A002496. %H A325439 Robert Israel, <a href="/A325439/b325439.txt">Table of n, a(n) for n = 1..10000</a> %F A325439 A002496(a(n)) mod 10 = 7. %p A325439 P:=[seq(k mod 10,k=select(isprime,[2,seq(4*i^2+1,i=1..10000)]))]: %p A325439 seq(`if`(P[i] mod 10 = 7,i,NULL),i=1..nops(P)); %Y A325439 Cf. A002496, A325437, A325438. %K A325439 nonn,base %O A325439 1,1 %A A325439 _Martin Renner_, Apr 27 2019