A274392 A diagonal of rectangular array A274390 of coefficients in the iterations of Euler's tree function (A000169).

1, 4, 63, 2056, 112625, 9266706, 1067280319, 163802295616, 32300931452769, 7956776354536450, 2394142654816299431, 863996246301971667600, 368314015001746325448313, 183100281424495288847092386, 104989565698848905178879275775, 68778360046311927838608116567296, 51049027217135211093037275781929857, 42614907995326324626989103964953188610, 39750079580111447237206552931429888023399, 41188867531604111691413161924808444678694800, 47163303540183246052916530453746351377795346681

Offset: 1

Author

Paul D. Hanna, Jun 24 2016

Keywords

• nonn

Links

• Paul D. Hanna, Table of n, a(n) for n = 1..100

Crossrefs

Cf. A274390, A000169, A274389.

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 a diagonal of A274390 */
for(n=1,20,print1(A274390(n,n),", "))