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 A112646 #10 Jan 04 2017 02:39:25
%S A112646 8,26,2186,1594322,7509466514979724803946715958257546,
%T A112646 13915193059764305937984450503671774362956903094026
%N A112646 Special solutions to abs(sigma(x+1) - sigma(x)) = 2 where x + 1 = 3^y.
%C A112646 The relevant computed exponents providing -1+3^z solutions for A112645 are 2, 3, 7, 13, 71, 103.
%C A112646 The next term, if it exists, is too large to include here. - _N. J. A. Sloane_, Jul 12 2009
%C A112646 Contribution from _David Wasserman_, Jul 06 2009: No more terms < 10^86.
%t A112646 ta={{0}};Do[s=Abs[DivisorSigma[1, 3^n]-DivisorSigma[1, -1+3^n]]; If[Equal[s, 2], ta=Append[ta, n];Print[ -1+3^n]], {n, 1, 100000000}]; ta=Delete[ta, 1]
%Y A112646 Cf. A000203, A112645, A112647.
%K A112646 nonn
%O A112646 1,1
%A A112646 _Labos Elemer_, Sep 28 2005