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 A109223 #9 Mar 10 2019 01:43:15 %S A109223 1,1,1,1,1,1,1,3,1,1,1,3,5,1,1,1,6,5,7,1,1,1,6,15,7,9,1,1,1,10,15,28, %T A109223 9,11,1,1,1,10,35,28,45,11,13,1,1,1,15,35,84,45,66,13,15,1,1,1,15,70, %U A109223 84,165,66,91,15,17,1,1,1,21,70,210,165,286,91,120,17,19,1,1,1,21,126,210 %N A109223 Number triangle related to the Fibonacci polynomials. %C A109223 Riordan array (1/(1-x), x/(1-x^2)^2). Row-reversal of number triangle A109221. Diagonals form a repeated version of A054142. Row sums are A109222. Diagonal sums are A094967. %F A109223 T(n,k) = binomial(floor((n+k)/2)+k, 2*k) %F A109223 T(n,k) = A065941(n+k,n-k). - _Johannes W. Meijer_, Aug 14 2011 %e A109223 Rows begin %e A109223 1; %e A109223 1, 1; %e A109223 1, 1, 1; %e A109223 1, 3, 1, 1; %e A109223 1, 3, 5, 1, 1; %e A109223 1, 6, 5, 7, 1, 1; %e A109223 1, 6, 15, 7, 9, 1, 1; %p A109223 A109223 := proc(n,k): binomial(floor((n+k)/2)+k, 2*k) end: seq(seq(A109223(n,k), k=0..n), n=0..11); # _Johannes W. Meijer_, Aug 14 2011 %K A109223 easy,nonn,tabl %O A109223 0,8 %A A109223 _Paul Barry_, Jun 22 2005