A306013 - OEIS

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A306013

Let P(m) be the product of unitary divisors of m; then a(n) is the position of P(n) when all the numbers P(m) are arranged in increasing order.

1, 2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25, 27, 29, 31, 32, 36, 37, 41, 43, 47, 49, 53, 59, 61, 64, 67, 71, 73, 79, 81, 83, 89, 97, 100, 144, 196, 225, 324, 400, 441, 484, 576, 676, 784, 1089, 1156, 1225, 1296, 1444, 1521, 1600, 1936, 2025, 2116

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OFFSET

1,2

COMMENTS

P(m) = A061537(m).

LINKS

Table of n, a(n) for n=1..58.

MATHEMATICA

z = 100; r[n_] := Select[Divisors[n], GCD[#, n/#] == 1 &];

k[n_] := Length[r[n]];

Table[r[n], {n, 1, z}]

a[n_] := Apply[Times, r[n]]