A344134 a(n) = Sum_{i|n, j|n, k|n} lcm(i,j,k).

1, 15, 22, 91, 36, 330, 50, 387, 193, 540, 78, 2002, 92, 750, 792, 1363, 120, 2895, 134, 3276, 1100, 1170, 162, 8514, 511, 1380, 1192, 4550, 204, 11880, 218, 4275, 1716, 1800, 1800, 17563, 260, 2010, 2024, 13932, 288, 16500, 302, 7098, 6948, 2430, 330, 29986, 981, 7665, 2640, 8372, 372, 17880

Offset

1,2

Links

Table of n, a(n) for n=1..54.

Formula

a(n) = Sum_{i|n, j|n, k|n} n/gcd(i,j,k).

If p is prime, a(p) = 1 + 7*p.

Mathematica

a[n_]:= Sum[n/GCD[i, j, k], {i, (d = Divisors[n])}, {j, d}, {k, d}]; Array[a, 50] (* Amiram Eldar, May 10 2021 *)

Prog

(PARI) a(n) = sumdiv(n, i, sumdiv(n, j, sumdiv(n, k, lcm([i, j, k]))));
(PARI) a(n) = sumdiv(n, i, sumdiv(n, j, sumdiv(n, k, n/gcd([i, j, k]))));

Crossrefs

Cf. A064950, A344132, A344133, A344135.

Sequence in context: A186525 A236107 A065728 * A241253 A317793 A219683

Adjacent sequences: A344131 A344132 A344133 * A344135 A344136 A344137

Keyword

nonn,mult

Author

Seiichi Manyama, May 10 2021

Status

approved