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 A260988 #10 Jan 17 2020 10:44:41
%S A260988 8505,25500,30360,37740,40740,123795,141480,185460,442365,485400,
%T A260988 834435,953568,1055460,1097820,1108320,1397220,1953960,2088480,
%U A260988 2208840,2571744,3050784,3342816,3544695,3810456,4314156,4725660,4867236,5638776,6318180,6596340,8428320,8630832,9347280,9576336,9908460,10271580,10992360,11789925
%N A260988 Numbers n such that sigma(n) = m*sigma(n+2) with some m > 1.
%C A260988 Sequence A227304 is the union of A055574 and { a(n)+1 }.
%C A260988 Many but not all terms are multiples of 5.
%o A260988 (PARI) for(n=1,2e9,sigma(n)%sigma(n+2)||sigma(n)==sigma(n+2)||print1(n","))
%Y A260988 Cf. A000203, A055574, A067130, A058073.
%K A260988 nonn
%O A260988 1,1
%A A260988 _M. F. Hasler_, Aug 06 2015