A120785 Denominators of partial sums of Catalan numbers scaled by powers of 1/16.

1, 16, 128, 4096, 32768, 524288, 4194304, 268435456, 2147483648, 34359738368, 274877906944, 8796093022208, 70368744177664, 1125899906842624, 9007199254740992, 1152921504606846976

Offset: 0

Author

Wolfdieter Lang, Jul 20 2006

Keywords

• nonn
• easy
• frac

Comments

Numerators are given under A120784.

The listed numbers coincide with the denominators of sum(C(k)/(-16)^k,k=0..n). For the numerators see A120794. In general these denominators may be different. See e.g. A120783 versus A120793 and A120787 versus A120796.

Also one fourth of denominators of partial sums for sqrt(2)+sqrt(3). See A121503 for the numerators.

Formula

a(n)=denominator(r(n)), with the rationals r(n):=sum(C(k)/16^k,k=0..n) with C(k):=A000108(k) (Catalan numbers).