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A238428 Expansion of F(x) where F(x) = 1 + x / (1 - x * F(x) - x^2 * F(x^2) ). 1
1, 1, 1, 3, 6, 17, 42, 118, 321, 920, 2626, 7679, 22554, 67115, 200883, 606238, 1839448, 5613892, 17211963, 53006846, 163866246, 508389780, 1582286912, 4939146731, 15459006948, 48505063741, 152539740067, 480726546083, 1517979996460, 4802074019769, 15217153748772, 48298352064093, 153526087484475 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

What does this sequence count?

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..500

FORMULA

a(n) ~ c * d^n / n^(3/2), where d = 3.3305741143240040687593..., c = 0.544842763137687191994... . - Vaclav Kotesovec, Aug 22 2014

PROG

(PARI)

N=66;  R=O('x^N);  x='x+R;

F = 1;  for (k=1, N+1, F = 1 + x / (1 - x * F - x^2 * subst(F, 'x, 'x^2) ) + R; );

Vec(F)

CROSSREFS

Sequence in context: A089264 A121399 A212421 * A232771 A129905 A143363

Adjacent sequences:  A238425 A238426 A238427 * A238429 A238430 A238431

KEYWORD

nonn

AUTHOR

Joerg Arndt, Feb 28 2014

STATUS

approved

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Last modified June 16 21:55 EDT 2021. Contains 345080 sequences. (Running on oeis4.)