A120781 Denominators of partial sums of Catalan numbers scaled by powers of 1/8.

1, 8, 32, 512, 2048, 16384, 65536, 2097152, 8388608, 67108864, 268435456, 4294967296, 17179869184, 137438953472, 549755813888, 35184372088832, 140737488355328, 1125899906842624, 4503599627370496, 72057594037927936

Offset

0,2

Comments

Numerators are given under A120780.

The listed numbers coincide with denominators of sum(C(k)/(-8)^k,k=0..n). For the numerators see A120789. In general these denominators may be different. See e.g. A120783 versus A120793 and A120787 versus A120796.

Links

Table of n, a(n) for n=0..19.

Formula

a(n)=denominator(r(n)), with the rationals r(n):=sum(C(k)/8^k,k=0..n) with C(k):=A000108(k) (Catalan numbers).

Crossrefs

Sequence in context: A159277 A214539 A140789 * A288454 A139286 A139306

Adjacent sequences: A120778 A120779 A120780 * A120782 A120783 A120784

Keyword

nonn,easy,frac

Author

Wolfdieter Lang, Jul 20 2006

Status

approved