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 A117389 #2 Mar 30 2012 18:59:14
%S A117389 1,0,1,0,1,1,0,0,3,1,0,0,1,5,1,0,0,0,5,7,1,0,0,0,1,13,9,1,0,0,0,0,7,
%T A117389 25,11,1,0,0,0,0,1,25,41,13,1,0,0,0,0,0,9,63,61,15,1,0,0,0,0,0,1,41,
%U A117389 129,85,17,1
%N A117389 A skew Delannoy number triangle read by rows.
%C A117389 Row sums are the trinomial numbers A000073(n+2). Diagonal sums are A079973.
%F A117389 Number triangle T(n,k)=[k<=n]*sum{j=0..2k-n, C(2k-n,j)C(n-k,j)2^j}; T(n,k)=sum{j=0..2k-n, C(2k-n,j)C(n-k,n-k-j)2^j};
%e A117389 Triangle begins
%e A117389 1,
%e A117389 0, 1,
%e A117389 0, 1, 1,
%e A117389 0, 0, 3, 1,
%e A117389 0, 0, 1, 5, 1,
%e A117389 0, 0, 0, 5, 7, 1,
%e A117389 0, 0, 0, 1, 13, 9, 1,
%e A117389 0, 0, 0, 0, 7, 25, 11, 1
%Y A117389 Cf. A008288.
%K A117389 easy,nonn,tabl
%O A117389 0,9
%A A117389 _Paul Barry_, Mar 11 2006