A349440 - OEIS

A349440

a(n) = n / gcd(A001608(n), n), where A001608 = Perrin sequence.

1, 1, 1, 2, 1, 6, 1, 4, 3, 10, 1, 12, 1, 14, 15, 8, 1, 9, 1, 20, 21, 11, 1, 24, 5, 26, 9, 28, 1, 3, 1, 16, 33, 34, 35, 18, 1, 38, 13, 8, 1, 14, 1, 22, 45, 23, 1, 16, 7, 25, 51, 52, 1, 54, 55, 56, 57, 29, 1, 30, 1, 62, 63, 32, 65, 22, 1, 68, 69, 70, 1, 36, 1, 37, 75, 76, 77, 13, 1, 16, 27, 82, 1, 84, 85, 43, 29, 44

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OFFSET

1,4

COMMENTS

The first composite n with a(n) = 1 is n = 521^2 = 271441. See comments in A001608.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = n / A086847(n) = n / gcd(A001608(n), n).

MATHEMATICA

p[1] = 0; p[2] = 2; p[3] = 3; p[n_] := p[n] = p[n - 2] + p[n - 3]; a[n_] := n/GCD[p[n], n]; Array[a, 100] (* Amiram Eldar, Nov 22 2021 *)

PROG