A328478 - OEIS

A328478

Divide n by the largest primorial that divides it and repeat until a fixed point is reached; a(n) is the fixed point.

1, 1, 3, 1, 5, 1, 7, 1, 9, 5, 11, 1, 13, 7, 15, 1, 17, 3, 19, 5, 21, 11, 23, 1, 25, 13, 27, 7, 29, 1, 31, 1, 33, 17, 35, 1, 37, 19, 39, 5, 41, 7, 43, 11, 45, 23, 47, 1, 49, 25, 51, 13, 53, 9, 55, 7, 57, 29, 59, 1, 61, 31, 63, 1, 65, 11, 67, 17, 69, 35, 71, 1, 73, 37, 75, 19, 77, 13, 79, 5, 81, 41, 83, 7, 85, 43, 87, 11, 89

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OFFSET

1,3

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..30030

Index entries for sequences related to primorial numbers

FORMULA

If A111701(n) == n, then a(n) = n, otherwise a(n) = a(A111701(n)).

a(n) = n / A328479(n).

MATHEMATICA

A111701[n_] := A111701[n] = Block[{m = n, k = 1}, While[IntegerQ[m/Prime[k]], m = m/Prime[k]; k++]; m];

a[n_] := a[n] = If[A111701[n] == n, n, a[A111701[n]]];