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 A140210 #23 Jan 07 2021 06:59:26
%S A140210 1,1,1,1,5,1,1,1,9,5,1,1,13,1,5,1,17,9,1,5,21,1,1,1,125,13,9,1,29,5,1,
%T A140210 1,33,17,5,9,37,1,13,5,41,21,1,1,2025,1,1,1,49,125,17,13,53,9,5,1,57,
%U A140210 29,1,5,61,1,189,1,4225,33,1,17,69,5,1,9,73,37,125,1,77,13,1,5,729,41,1,21
%N A140210 a(n) = Product_{h == 1 (mod 4) and h|n} h.
%H A140210 Alois P. Heinz, <a href="/A140210/b140210.txt">Table of n, a(n) for n = 1..10000</a>
%p A140210 with(numtheory):
%p A140210 a:= n-> mul(i, i=select(h-> irem(h, 4)=1, divisors(n))):
%p A140210 seq(a(n), n=1..120); # _Alois P. Heinz_, Jul 28 2009
%t A140210 a[n_] := Times @@ Select[Divisors[n], Mod[#, 4] == 1&]; Table[a[n], {n, 1, 120}] (* _Jean-François Alcover_, Jun 24 2015 *)
%o A140210 (PARI) a(n) = my(p=1); fordiv(n, d, if ((d % 4)==1, p*=d)); p; \\ _Michel Marcus_, Jan 07 2021
%Y A140210 Cf. A007955, A140211, A136655, A140213, A140214, A140215, A136655.
%K A140210 nonn,look
%O A140210 1,5
%A A140210 _R. J. Mathar_, Jun 27 2008
%E A140210 More terms from _Alois P. Heinz_, Jul 28 2009