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 A234002 #9 Dec 27 2013 03:01:00 %S A234002 1,1,4,4,1,1,2,4,3,1,4,4,1,1,2,8,1,3,4,4,1,1,2,4,5,1,36,4,1,1,2,16,1, %T A234002 1,4,12,1,1,2,4,1,1,4,4,3,1,2,8,7,5,4,4,1,9,2,4,1,1,4,4,1,1,6,32,1,1, %U A234002 4,4,1,1,2,12,1,1,20,4,1,1,2,8,27,1,4,4,1,1,2,4,1,3,4,4,1,1,2 %N A234002 4n/A234001(n). %C A234002 Please look into A234001 for a more detailed description. %C A234002 If n is squarefree and n == 1 (mod 4) or n == 2 (mod 4), then a(n) = 1. %C A234002 If p^2 divides n for some prime p, a(n) is a multiple of p. %C A234002 If n == 3 (mod 8), then a(n) is a multiple of 4 because numbers of the form x^2+n*y^2 cannot have any prime factors that are congruent to 2+n (mod 2n) raised to an odd power. %C A234002 If n == 7 (mod 8), then a(n) is a multiple of 2 because numbers of the form x^2+n*y^2 can have prime factors that are congruent to 2+n (mod 2n) raised to an odd power, but they cannot be congruent to 2 (mod 4). So, we need to characterize the prime factor of 2 from the remaining prime factors that are congruent to 2+n (mod 2n) separately. %Y A234002 Cf. A000926, A232550, A232551, A234001. %K A234002 nonn,uned %O A234002 1,3 %A A234002 _V. Raman_, Dec 18 2013