A336319 Squarefree part of n*d(n), where d(n) = number of divisors of n (A000005).

1, 1, 6, 3, 10, 6, 14, 2, 3, 10, 22, 2, 26, 14, 15, 5, 34, 3, 38, 30, 21, 22, 46, 3, 3, 26, 3, 42, 58, 15, 62, 3, 33, 34, 35, 1, 74, 38, 39, 5, 82, 21, 86, 66, 30, 46, 94, 30, 3, 3, 51, 78, 106, 3, 55, 7, 57, 58, 118, 5, 122, 62, 42, 7, 65, 33, 134, 102, 69, 35, 142, 6, 146

Offset

1,3

Links

Antti Karttunen, Table of n, a(n) for n = 1..20000

Formula

a(n) = A007913(A038040(n)) = A007913(n*A000005(n)).

a(n) = A038040(n)/A000290(A336318(n)).

Mathematica

f[p_, e_] := p^Mod[e, 2]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n * DivisorSigma[0, n]]; Array[a, 100] (* Amiram Eldar, Feb 01 2025 *)

Prog

(PARI) A336319(n) = core(n*numdiv(n));

Crossrefs

Cf. A000005, A000290, A007913, A038040, A336318.

Cf. A069067 (positions of ones).

Sequence in context: A327000 A249948 A066070 * A376973 A272549 A112456

Adjacent sequences: A336316 A336317 A336318 * A336320 A336321 A336322

Keyword

nonn

Author

Antti Karttunen, Jul 18 2020

Status

approved