A328661 If n is the k-th composite number then a(n) = a(k), otherwise a(n) = n.

1, 2, 3, 1, 5, 2, 7, 3, 1, 5, 11, 2, 13, 7, 3, 1, 17, 5, 19, 11, 2, 13, 23, 7, 3, 1, 17, 5, 29, 19, 31, 11, 2, 13, 23, 7, 37, 3, 1, 17, 41, 5, 43, 29, 19, 31, 47, 11, 2, 13, 23, 7, 53, 37, 3, 1, 17, 41, 59, 5, 61, 43, 29, 19, 31, 47, 67, 11, 2, 13, 71, 23, 73

Offset: 1

Author

Rémy Sigrist, Oct 24 2019

Keywords

• nonn

Examples

			a(42) = a(28) = a(18) = a(10) = a(5) = 5.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000

Crossrefs

See A288469 and A328018 for similar sequences.

Cf. A002808, A006508.

Programs

PARI

k=0; for (n=1, #a=vector(73), print1 (a[n] = if (bigomega(n)>1, a[k++], n) ", "))

Formula

a(n) = 1 iff n belongs to A006508.