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 A136478 #9 Feb 23 2017 22:34:07 %S A136478 7,7,3,15,15,15,7,3,5,7,3,15,15,27,3,15,3,27,15,27,13,3,49,17,55,27, %T A136478 27,15,53,77,63,77,15,45,15,69,45,77,15,57,75,27,75,63,55,75,49,85,7,3 %N A136478 Smallest y such that for x = A136477(n), x^2 + x + y^2 is an odd primitive abundant number, A136476(n). %C A136478 See A136477 and A136476 for the x-values and the abundant numbers x^2 + x + y^2. %F A136478 a(n) = sqrt(A136476(n) - A136477(n)^2 - A136477(n)). - _M. F. Hasler_, Feb 22 2017 %e A136478 97^2+97+7^2 = 9555 = A136476(1) is an odd primitive abundant number, therefore a(1) = 7. %o A136478 (PARI) {for(x=1, 5000, my(n=x^2+x+1, f); forstep(y=1, sqrtint(2*x), 2, sigma(n+=y*4-4, -1)>2 || next; for(i=1, #f=factor(n)[, 1], sigma(n\f[i], -1)>2 && next(2)); print1(y","); break))} \\ _M. F. Hasler_, Feb 22 2017 %Y A136478 Cf. A006038, A136476, A136477, A136479. %K A136478 nonn %O A136478 1,1 %A A136478 _Pierre CAMI_, Dec 31 2007 %E A136478 Edited by _M. F. Hasler_, Feb 22 2017