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 A038222 #12 Jul 08 2025 22:10:41
%S A038222 1,3,4,9,24,16,27,108,144,64,81,432,864,768,256,243,1620,4320,5760,
%T A038222 3840,1024,729,5832,19440,34560,34560,18432,4096,2187,20412,81648,
%U A038222 181440,241920,193536,86016,16384,6561,69984,326592,870912,1451520
%N A038222 Triangle whose (i,j)-th entry is binomial(i,j)*3^(i-j)*4^j.
%H A038222 B. N. Cyvin et al., <a href="http://match.pmf.kg.ac.rs/electronic_versions/Match34/match34_109-121.pdf">Isomer enumeration of unbranched catacondensed polygonal systems with pentagons and heptagons</a>, Match, No. 34 (Oct 1996), pp. 109-121.
%F A038222 G.f.: 1/(1 - 3*x - 4*x*y). - _Ilya Gutkovskiy_, Apr 21 2017
%t A038222 Table[Binomial[i,j]3^(i-j) 4^j,{i,0,10},{j,0,i}]//Flatten (* _Harvey P. Dale_, Oct 02 2021 *)
%K A038222 nonn,tabl,easy
%O A038222 0,2
%A A038222 _N. J. A. Sloane_