A274389 Main diagonal of rectangular array A274390 of coefficients in the iterations of Euler's tree function (A000169).

1, 2, 30, 948, 50680, 4090980, 463975764, 70311813880, 13718193268896, 3348658563980040, 999698412743754460, 358297471515195652308, 151813934699349280088328, 75064081768759279536110316, 42833194538353991390132088540, 27937122503026656234469859408880, 20653210428143999114034181337343616, 17178393944175652034128269331788145680, 15970217696130529428248774113884778921452, 16497536217367322285994072192399435877530380, 18836957575278690757486149667782477659475272520

Offset: 0

Author

Paul D. Hanna, Jun 24 2016

Keywords

• nonn

Links

• Paul D. Hanna, Table of n, a(n) for n = 0..100

Crossrefs

Cf. A274390, A000169, A274392.

Programs

PARI

{ITERATE(F,n,k) = my(G=x +x*O(x^k)); for(i=1,n,G=subst(G,x,F));G}
{A274390(n,k) = my(TREE = serreverse(x*exp(-x +x*O(x^k)))); k!*polcoeff(ITERATE(TREE,n,k),k)}
/* Print A274390 */
for(n=0,10,for(k=1,10,print1(A274390(n,k),", "));print("..."))
/* Print this sequence, as the main diagonal of A274390 */
for(n=0,20,print1(A274390(n,n+1),", "))