A319088 a(n) = Sum_{k=1..n} k^2*tau_3(k), where tau_3 is A007425.
1, 13, 40, 136, 211, 535, 682, 1322, 1808, 2708, 3071, 5663, 6170, 7934, 9959, 13799, 14666, 20498, 21581, 28781, 32750, 37106, 38693, 55973, 59723, 65807, 73097, 87209, 89732, 114032, 116915, 138419, 148220, 158624, 169649, 216305, 220412, 233408, 247097
Offset: 1
Keywords
Links
- G. C. Greubel, Table of n, a(n) for n = 1..10000
- Eric Weisstein's World of Mathematics, Stieltjes Constants
- Wikipedia, Stieltjes constants
Programs
-
Mathematica
nmax = 50; Accumulate[Table[k^2*Sum[DivisorSigma[0, d], {d, Divisors[k]}], {k, 1, nmax}]] -
PARI
tau_3(k) = vecprod(apply(e -> (e+1)*(e+2)/2, factor(k)[, 2])); a(n) = sum(k = 1, n, k^2 * tau_3(k)); \\ Amiram Eldar, Jan 18 2025