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A122889 Antidiagonal sums of table A122888. 6
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified October 15 01:40 EDT 2019. Contains 328025 sequences. (Running on oeis4.)