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A052823 A simple grammar: cycles of pairs of sequences. 9
0, 0, 1, 2, 4, 6, 12, 18, 34, 58, 106, 186, 350, 630, 1180, 2190, 4114, 7710, 14600, 27594, 52486, 99878, 190744, 364722, 699250, 1342182, 2581426, 4971066, 9587578, 18512790, 35792566, 69273666, 134219794, 260301174, 505294126, 981706830, 1908881898 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 788

S. Saito, T. Tanaka, N. Wakabayashi, Combinatorial Remarks on the Cyclic Sum Formula for Multiple Zeta Values , J. Int. Seq. 14 (2011) # 11.2.4, Table 2.

FORMULA

G.f.: Sum(numtheory[phi](j[1])/j[1]*log(-(x^j[1]-1)^2/(2*x^j[1]-1)), j[1]=1 .. infinity).

MAPLE

spec := [S, {B=Sequence(Z, 1 <= card), C=Prod(B, B), S= Cycle(C)}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);

CROSSREFS

A000031 - 2.

Column k=2 of A087854.

Sequence in context: A259941 A007436 A052847 * A063516 A104352 A133488

Adjacent sequences:  A052820 A052821 A052822 * A052824 A052825 A052826

KEYWORD

easy,nonn

AUTHOR

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

EXTENSIONS

More terms from Alois P. Heinz, Jan 25 2015

STATUS

approved

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Last modified February 23 21:23 EST 2018. Contains 299588 sequences. (Running on oeis4.)