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 A320907 #14 Jan 11 2024 06:43:17
%S A320907 0,1,7,33,130,461,1525,4802,14577,43025,124226,352437,985821,2725858,
%T A320907 7466185,20291193,54791842,147164525,393517477,1048395650,2784568545,
%U A320907 7377137441,19503081602,51470797413,135641216685,357029910946,938837513785,2466747164937
%N A320907 Row sums of A320906.
%F A320907 Conjectures from _Colin Barker_, Oct 28 2018: (Start)
%F A320907 G.f.: x*(1 - x)^2 / ((1 - 2*x)^3*(1 - 3*x + x^2)).
%F A320907 a(n) = 9*a(n-1) - 31*a(n-2) + 50*a(n-3) - 36*a(n-4) + 8*a(n-5) for n>4. (End)
%F A320907 a(n) = Sum_{k=0..n} Sum_{j=0..2*n + 1 - k} binomial(2*n + 1 - k, 2*n + 2 - 2*k + j)*binomial(j + 2, 2). - _Detlef Meya_, Jan 09 2024
%t A320907 a[n_] := Sum[Sum[Binomial[2*n + 1 - k, 2*n + 2 - 2*k + j]*Binomial[j + 2, 2], {j, 0, 2*n + 1 - k}], {k, 0, n}]; Flatten[Table[a[n], {n, 0, 27}]] (* _Detlef Meya_, Jan 09 2024 *)
%Y A320907 Cf. A318947, A320906.
%K A320907 nonn
%O A320907 0,3
%A A320907 _Peter Luschny_, Oct 28 2018