A072695 a(n) = lcm(d(n^2),d(n)), where d(n) = A000005, the number of divisors of n.

1, 6, 6, 15, 6, 36, 6, 28, 15, 36, 6, 30, 6, 36, 36, 45, 6, 30, 6, 30, 36, 36, 6, 168, 15, 36, 28, 30, 6, 216, 6, 66, 36, 36, 36, 225, 6, 36, 36, 168, 6, 216, 6, 30, 30, 36, 6, 270, 15, 30, 36, 30, 6, 168, 36, 168, 36, 36, 6, 180, 6, 36, 30, 91, 36, 216, 6, 30, 36, 216, 6, 420

Offset

1,2

Links

Antti Karttunen, Table of n, a(n) for n = 1..16384

Index entries for sequences computed from exponents in factorization of n.

Index entries for sequences related to LCM.

Formula

If n is squarefree product of k distinct primes, then a(n) = 6^k.

If n = p^2, then a(n) = 15, etc.

Mathematica

Table[LCM[DivisorSigma[0, n], DivisorSigma[0, n^2]], {n, 80}] (* Harvey P. Dale, Dec 26 2018 *)

Prog

(PARI) A072695(n) = lcm(numdiv(n), numdiv(n^2)); \\ Antti Karttunen, Nov 24 2017
(PARI) a(n) = {my(e = factor(n)[, 2]); lcm(vecprod(apply(x -> 2*x+1, e)), vecprod(apply(x -> x+1, e))); } \\ Amiram Eldar, Dec 02 2023

Crossrefs

Cf. A000005, A072696.

Sequence in context: A110626 A339721 A341832 * A356574 A330568 A085596

Adjacent sequences: A072692 A072693 A072694 * A072696 A072697 A072698

Keyword

easy,nonn

Author

Labos Elemer, Jul 04 2002

Status

approved