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 A187680 #26 Jun 18 2022 04:03:57
%S A187680 0,2,3,1,5,0,7,4,1,10,11,20,13,4,9,1,17,21,19,20,25,16,23,36,1,4,9,0,
%T A187680 29,0,31,8,33,22,25,83,37,4,9,40,41,48,43,8,21,28,47,88,1,8,9,76,53,
%U A187680 96,1,16,49,34,59,120,61,4,31,1
%N A187680 a(n) = (product of divisors of n) mod (sum of divisors of n).
%H A187680 Harvey P. Dale, <a href="/A187680/b187680.txt">Table of n, a(n) for n = 1..1000</a>
%F A187680 a(n) = A007955(n) mod A000203(n).
%F A187680 a(n) = 0 iff n is in A145551 and a(n) = 1 iff n is in A188061. - _Amiram Eldar_, Jun 18 2022
%p A187680 A187680 := proc(n) A007955(n) mod numtheory[sigma](n) ; end proc:
%p A187680 seq(A187680(n),n=1..120) ; # _R. J. Mathar_, Mar 17 2011
%t A187680 Table[Mod[Times@@Divisors[n],DivisorSigma[1,n]],{n,70}] (* _Harvey P. Dale_, May 23 2021 *)
%t A187680 a[n_] := Mod[n^(DivisorSigma[0, n]/2), DivisorSigma[1, n]]; Array[a, 60] (* _Amiram Eldar_, Jun 18 2022 *)
%o A187680 (PARI) a(n) = my(d=divisors(n)); vecprod(d) % vecsum(d); \\ _Michel Marcus_, Jan 29 2019
%Y A187680 Cf. A000203, A007955, A145551, A188061.
%K A187680 nonn
%O A187680 1,2
%A A187680 _Juri-Stepan Gerasimov_, Mar 17 2011