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 A112157 #28 Jun 28 2018 08:49:26
%S A112157 1,-2,-1,4,-3,0,7,-8,-3,14,-14,-4,26,-26,-7,44,-41,-10,73,-72,-20,118,
%T A112157 -109,-28,182,-174,-47,280,-260,-66,419,-392,-102,618,-568,-144,898,
%U A112157 -832,-216,1292,-1178,-296,1828,-1676,-429,2568,-2334,-588,3570,-3248,-822,4920,-4446,-1114,6722,-6084
%N A112157 McKay-Thompson series of class 18i for the Monster group.
%H A112157 G. C. Greubel, <a href="/A112157/b112157.txt">Table of n, a(n) for n = 0..2500</a> (terms 0..1000 from Seiichi Manyama)
%H A112157 D. Ford, J. McKay and S. P. Norton, <a href="http://dx.doi.org/10.1080/00927879408825127">More on replicable functions</a>, Commun. Algebra 22, No. 13, 5175-5193 (1994).
%H A112157 <a href="/index/Mat#McKay_Thompson">Index entries for McKay-Thompson series for Monster simple group</a>
%F A112157 Euler transform of period 3 sequence [ -2,-2,0, ...]. - _Vladeta Jovovic_, Oct 20 2006
%F A112157 Expansion of q^(1/6)*(eta(q)/eta(q^3))^2 in powers of q. - _G. C. Greubel_, Jun 06 2018
%e A112157 T18i = 1/q -2*q^5 -q^11 +4*q^17 -3*q^23 +7*q^35 -8*q^41 +...
%p A112157 N := 60; series(mul(1+x^k+x^(2*k), k=1..N)^(-2),x=0,N); # _Mark van Hoeij_, Apr 19 2013
%t A112157 QP = QPochhammer; s = (QP[q]/QP[q^3])^2 + O[q]^60; CoefficientList[s, q] (* _Jean-François Alcover_, Nov 15 2015, adapted from PARI *)
%o A112157 (PARI) N=66; x='x+O('x^N); Vec( (eta(x)/eta(x^3))^2 ) \\ _Joerg Arndt_, Apr 20 2013
%K A112157 sign
%O A112157 0,2
%A A112157 _Michael Somos_, Aug 28 2005