A122889 Antidiagonal sums of table A122888.

1, 1, 2, 3, 6, 12, 27, 67, 180, 528, 1676, 5721, 20924, 81634, 338322, 1484209, 6870492, 33460830, 170997842, 914764494, 5111445917, 29773148141, 180449216699, 1136060712131, 7418026238304, 50163775035664

Offset

0,3

Comments

In table A122888, row n lists the coefficients of x^k, k=1..2^n, in the n-th self-composition of (x + x^2) for n>=0.

Links

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

Prog

(PARI) {a(n)=local(F=x+x^2, G, RS); RS=0; for(k=0, n, G=x+x*O(x^n); for(i=1, n-k, G=subst(F, x, G)); RS+=polcoeff(G, k, x)); RS} \\ Paul D. Hanna, Nov 28 2009

Crossrefs

Cf. A122888.

Sequence in context: A057649 A104872 A006082 * A014280 A073431 A273873

Adjacent sequences: A122886 A122887 A122888 * A122890 A122891 A122892

Keyword

nonn

Author

Paul D. Hanna, Sep 18 2006

Status

approved