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 A024517 #10 Apr 01 2025 17:53:26 %S A024517 1,3,7,12,18,25,34,45,56,68,82,95,112,128,146,164,183,205,227,250,275, %T A024517 300,325,350,382,410,440,470,503,536,569,605,642,678,717,752,794,837, %U A024517 878,918,963,1007,1054,1101,1147,1196,1246,1293,1348,1401,1452,1506 %N A024517 Position of 2*n^2 in A000404 (sums of 2 nonzero squares). %H A024517 Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 03 2008, <a href="/A024517/b024517.txt">Table of n, a(n) for n = 1..130</a> %o A024517 (PARI) i=0;for(n=1,1000000,f=factor(n);r=0;b=0;t=0;for(k=1,#f[,1],if(f[k,1]%4==1,r++,if(f[k,1]%4==3,b+=(f[k,2]%2),t=(f[k,2]%2)))); if(b==0 && (r>0 || t==1), i++; if(issquare(n/2),print1(i",")))) \\ Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 03 2008 %K A024517 nonn %O A024517 1,2 %A A024517 _Clark Kimberling_ %E A024517 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 03 2008