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

Author

Paul D. Hanna, Sep 18 2006

Keywords

• nonn

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.

Crossrefs

Cf. A122888.

Programs

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