%I #12 Jan 28 2020 09:00:45

%S 1,4,30,284,3217,42100,621936,10206956,183946656,3608229588,

%T 76499111202,1742909621024,42465280193704,1101811478508828,

%U 30331386700718440,883010853509597608,27105284242369828508,874996700615422755068

%N Column 3 of triangle A127126.

%C Self-convolution 4th power of A127133.

%H G. C. Greubel, <a href="/A127130/b127130.txt">Table of n, a(n) for n = 3..80</a>

%t T[n_, k_]:= T[n, k]= If[k==n, 1, Coefficient[(1 +x*Sum[x^(r-k-1)*Sum[T[r, c], {c, k+1, r}], {r, k+1, n}] + x^(n+1))^(k+1), x, n-k]]; Table[T[n, 3], {n, 3, 20}] (* _G. C. Greubel_, Jan 28 2020 *)

%Y Cf. A127126; A127133; other columns: A127127, A127128, A127129.

%K nonn

%O 3,2

%A _Paul D. Hanna_, Jan 05 2007