A378930 a(n) = n * d(n) / gcd(n, d(n))^2, where d = A000005.

1, 1, 6, 12, 10, 6, 14, 2, 3, 10, 22, 2, 26, 14, 60, 80, 34, 3, 38, 30, 84, 22, 46, 3, 75, 26, 108, 42, 58, 60, 62, 48, 132, 34, 140, 4, 74, 38, 156, 5, 82, 84, 86, 66, 30, 46, 94, 120, 147, 75, 204, 78, 106, 108, 220, 7, 228, 58, 118, 5, 122, 62, 42, 448, 260

Offset

1,3

Links

Viliam Furík, Table of n, a(n) for n = 1..10000

Formula

a(n) = A038040(n)/A009191(n)^2.

a(n) = A009230(n)/A009191(n).

Maple

a:= n-> (d-> n*d/igcd(n, d)^2)(numtheory[tau](n)):
seq(a(n), n=1..65);  # Alois P. Heinz, Dec 11 2024

Mathematica

a[n_]:= n * DivisorSigma[0, n]/GCD[n, DivisorSigma[0, n]]^2; Array[a, 65] (* Stefano Spezia, Dec 11 2024 *)

Prog

(PARI) a(n) = my(d = numdiv(n)); n * d / gcd(n, d)^2; \\ Amiram Eldar, Dec 11 2024

Crossrefs

Cf. A000005, A009191, A009230, A038040.

Sequence in context: A243033 A242549 A315777 * A372453 A279606 A352482

Adjacent sequences: A378927 A378928 A378929 * A378931 A378932 A378933

Keyword

nonn

Author

Viliam Furík, Dec 11 2024

Status

approved