OFFSET
1,1
COMMENTS
The average value of a(n) is Pi^(3/2) * sqrt(n) * 2^(2*n+1) / 9.
MATHEMATICA
Table[Sum[Binomial[2*k, k]*DivisorSigma[1, k], {k, 1, n}], {n, 1, 30}]
PROG
(PARI) a(n) = sum(k=1, n, binomial(2*k, k) * sigma(k)); \\ Michel Marcus, Aug 05 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Aug 04 2022
STATUS
approved