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 A107972 #6 Feb 27 2015 09:22:22
%S A107972 1,3,6,6,14,20,10,25,40,50,15,39,66,90,105,21,56,98,140,175,196,28,76,
%T A107972 136,200,260,308,336,36,99,180,270,360,441,504,540,45,125,230,350,475,
%U A107972 595,700,780,825,55,154,286,440,605,770,924,1056,1155,1210,66,186,348
%N A107972 Triangle read by rows: T(n,k) = (k+1)(k+2)(n+2)(3n-2k+3)/12 for 0<=k<=n.
%C A107972 Kekulé numbers for certain benzenoids. Column 0 yields the triangular numbers (A000217). Row sums yield A006414. T(n,n) = A002415(n+2).
%D A107972 S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 237; K{B(n,2,l)}).
%e A107972 Triangle begins:
%e A107972 1;
%e A107972 3,6;
%e A107972 6,14,20;
%e A107972 10,25,40,50;
%p A107972 T:=proc(n,k) if k<=n then (k+1)*(k+2)*(n+2)*(3*n-2*k+3)/12 else 0 fi end: for n from 0 to 10 do seq(T(n,k),k=0..n) od; # yields sequence in triangular form
%Y A107972 Cf. A000217, A006414, A002415.
%K A107972 nonn,tabl
%O A107972 0,2
%A A107972 _Emeric Deutsch_, Jun 12 2005