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 A081954 #7 Dec 05 2013 19:56:03
%S A081954 2,4,6,8,12,18,16,24,36,54,32,48,72,108,162,64,96,144,216,324,486,128,
%T A081954 192,288,432,648,972,1458,256,384,576,864,1296,1944,2916,4374,512,768,
%U A081954 1152,1728,2592,3888,5832,8748,13122,1024,1536,2304,3456,5184,7776
%N A081954 Triangle read by rows: T(n, k) = 2^(n-k)*3^k, n >= 1, 0 <= k < n.
%e A081954 Triangle begins:
%e A081954 2
%e A081954 4 6
%e A081954 8 12 18
%e A081954 16 24 36 54
%e A081954 32 48 72 108 162
%e A081954 ...
%o A081954 (PARI) tabl(nrows) = {for (n=1, nrows, for (k=0, n-1, print1(2^(n-k)*3^k, ", ");); print(););} \\ _Michel Marcus_, May 14 2013
%Y A081954 Leading diagonal is given by A025192.
%Y A081954 Cf. A025192, A081955, A081956, A002262, A090404.
%K A081954 nonn,tabl
%O A081954 1,1
%A A081954 _Amarnath Murthy_, Apr 02 2003
%E A081954 Corrected and extended by _David Wasserman_, Jul 21 2004