A091469 - OEIS

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A091469

Number of unlabeled alternating octupi with n black nodes.

0

2, 9, 26, 85, 274, 981, 3498, 13005, 48818, 186193, 716474, 2782657, 10878642, 42792797, 169181578, 671878845, 2678679362, 10716700257, 43007271770, 173072733629, 698235687858, 2823329921445, 11439823954666, 46440711992697

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..24.

C. G. Bower, Transforms (2)

FORMULA

G.f.: A(x) = Sum_{k>=1} (phi(k)/k)*log((1-7*x^n+2*x^(2*n))/(1-x^n)^2).

CIK transform of A016825(n+1) i.e. b(n)=4n-2.

CROSSREFS

Row sums of A091467.

Sequence in context: A213387 A215184 A136429 * A125670 A222660 A182325

Adjacent sequences: A091466 A091467 A091468 * A091470 A091471 A091472

KEYWORD

nonn

AUTHOR

Christian G. Bower, Jan 12 2004

STATUS

approved