A344508 a(n) = Sum_{k=1..n} k * lcm(k,n).

1, 6, 24, 64, 175, 270, 686, 928, 1647, 2150, 4356, 3792, 8619, 8526, 11250, 14592, 25721, 19926, 40432, 31200, 44835, 53966, 87814, 58272, 108125, 106470, 132678, 124656, 224547, 132750, 294066, 232960, 284229, 316166, 372400, 291168, 600991, 496014, 560742, 484000, 909421, 531846

Offset: 1

Author

Seiichi Manyama, May 21 2021

Keywords

• nonn

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A051193, A057660, A344509, A344510.

Programs

Mathematica

a[n_] := Sum[k * LCM[k, n], {k, 1, n}]; Array[a, 50] (* Amiram Eldar, May 21 2021 *)

PARI

a(n) = sum(k=1, n, k*lcm(k, n));

Formula

Sum_{k=1..n} a(k) ~ 2 * zeta(3) * n^5 / (5*Pi^2). - Vaclav Kotesovec, May 29 2021