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 A033870 #13 Feb 17 2017 08:46:10
%S A033870 1,9,13,21,33,49,57,61,77,117,121,133,169,209,273,361,429,441,549,637,
%T A033870 693,741,793,1001,1089,1197,1281,1521,1573,1617,1729,1881,2013,2541,
%U A033870 2717,2793,2989,3249,3477,3549,4389,4693,4697,5577,5733,5929
%N A033870 Divisors = 1 (mod 4) of Descartes's 198585576189.
%C A033870 The number 198585576189 has 486 divisors, 246 of which are congruent to 1 modulo 4. - _M. F. Hasler_, Feb 17 2017
%H A033870 M. F. Hasler, <a href="/A033870/b033870.txt">Table of n, a(n) for n = 1..246</a>
%e A033870 198585576189 = 3^2 * 7^2 * 11^2 * 13^2 * 19^2 * 61.
%o A033870 (PARI) lista() = {fordiv(198585576189, d, if (d % 4 == 1, print1(d, ", ")));} \\ _Michel Marcus_, Jul 14 2013
%o A033870 (PARI) select(d->d%4==1, divisors(198585576189)) \\ _M. F. Hasler_, Feb 17 2017
%Y A033870 Cf. A033871, A222262.
%K A033870 easy,fini,nonn,full
%O A033870 1,2
%A A033870 _Naohiro Nomoto_
%E A033870 Corrected by _Michel Marcus_, Jul 14 2013