A353783 a(n) = LCM_{p^e||n} sigma(p^e), where n = Product_{p^e||n}, with each p^e the maximal power of prime p that divides n.

1, 3, 4, 7, 6, 12, 8, 15, 13, 6, 12, 28, 14, 24, 12, 31, 18, 39, 20, 42, 8, 12, 24, 60, 31, 42, 40, 56, 30, 12, 32, 63, 12, 18, 24, 91, 38, 60, 28, 30, 42, 24, 44, 84, 78, 24, 48, 124, 57, 93, 36, 14, 54, 120, 12, 120, 20, 30, 60, 84, 62, 96, 104, 127, 42, 12, 68, 126, 24, 24, 72, 195, 74, 114, 124, 140, 24, 84, 80

Offset: 1

Author

Antti Karttunen, May 08 2022

Keywords

• nonn

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A080398, A087207, A351560, A353784, A353785.

Cf. also A345044, A345046.

Cf. A336547 (positions where equal to sigma).

Programs

Mathematica

Array[LCM @@ DivisorSigma[1, Power @@@ FactorInteger[#]] &, 79] (* Michael De Vlieger, May 08 2022 *)

PARI

A353783(n) = { my(f=factor(n)~); lcm(vector(#f, i, sigma(f[1, i]^f[2, i]))); };

Formula

a(n) = A000203(n) / A353784(n).

a(n) = A353785(n) * A080398(n).

For all n >= 1, A087207(a(n)) = A351560(n).