OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
H. Cohen, Sums involving the values at negative integers of L-functions of quadratic characters, Math. Ann. 217 (1975), no. 3, 271-285. MR0382192 (52 #3080)
FORMULA
a(n) = - Sum_{k in Z} (k^4-3*n*k^2+n^2)*H(4*n-k^2) where H() is the Hurwitz class number.
MATHEMATICA
f[n_] := Block[{d = Divisors@n}, Plus @@ (Min[#, n/#]^5 & /@ d)]; Array[f, 57] (* Robert G. Wilson v, Jan 06 2018 *)
PROG
(PARI) {a(n) = sumdiv(n, d, min(d, n/d)^5)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jan 06 2018
STATUS
approved