OFFSET
0,3
COMMENTS
LINKS
Chai Wah Wu, Table of n, a(n) for n = 0..1659
Simon Demers, Taylor's Law Holds for Finite OEIS Integer Sequences and Binomial Coefficients, American Statistician, online: 19 Jan 2018.
FORMULA
EXAMPLE
The first few population variances are 0, 0, 2/9, 1, 94/25, 122/9, 2372/49, 173, 50294/81, 56014/25, 983740/121, 266930/9, 18376812/169, 19624884/49, 333313544/225, 5500541, 5923399334/289, ...
PROG
(Python)
from fractions import Fraction
from sympy import binomial
def A301631(n):
return (Fraction(int(binomial(2*n, n)))/(n+1) - Fraction(4**n)/(n+1)**2).numerator
(PARI) a(n) = numerator(binomial(2*n, n)/(n+1) - 4^n/(n+1)^2); \\ Altug Alkan, Mar 25 2018
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
N. J. A. Sloane and Chai Wah Wu, Mar 24 2018
STATUS
approved