OFFSET
1,5
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 1..10000
FORMULA
PROG
(Python)
from sympy import divisor_sigma
def A374977(n): return sum((5*divisor_sigma(i+1, 3)-(5+6*i)*divisor_sigma(i+1))*(5*divisor_sigma(n-i-1, 3)-(5+6*(n-i-2))*divisor_sigma(n-i-1)) for i in range(1, n-2))//144
CROSSREFS
KEYWORD
nonn
AUTHOR
Chai Wah Wu, Jul 26 2024
STATUS
approved