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

1,2

Links

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

Prog

(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), ", "))

Crossrefs

Cf. A274390, A000169, A274389.

Sequence in context: A293860 A349075 A299428 * A237644 A024256 A292394

Adjacent sequences: A274389 A274390 A274391 * A274393 A274394 A274395

Keyword

nonn

Author

Paul D. Hanna, Jun 24 2016

Status

approved