A322672 - OEIS

A322672

a(n) = Product_{d|n} (pod(d)/d) where pod(k) is the product of the divisors of k (A007955).

1, 1, 1, 2, 1, 6, 1, 16, 3, 10, 1, 1728, 1, 14, 15, 1024, 1, 5832, 1, 8000, 21, 22, 1, 191102976, 5, 26, 81, 21952, 1, 24300000, 1, 1048576, 33, 34, 35, 470184984576, 1, 38, 39, 4096000000, 1, 130691232, 1, 85184, 91125, 46, 1, 64925062108545024, 7, 125000, 51

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OFFSET

1,4

LINKS

Table of n, a(n) for n=1..51.

FORMULA

a(n) = n for n = 1 and squarefree semiprimes (A006881).

EXAMPLE

For n = 6; a(6) = pod(1)/1 * pod(2)/2 * pod(3)/3 * pod(6)/6 = 1/1 * 2/2 * 3/3 * 36/6 = 6.

MATHEMATICA

Array[Product[Apply[Times, Divisors@ d]/d, {d, Divisors@ #}] &, 51] (* Michael De Vlieger, Jan 19 2019 *)

PROG