A107286 a(0) = 0; for n>0, minimal prime factor of n, or 1 if n is 1 or a prime.

0, 1, 1, 1, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 5, 2, 3, 2, 1, 2, 1, 2, 3, 2, 5, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 7, 2, 3, 2, 1, 2, 5, 2, 3, 2, 1, 2, 1, 2, 3, 2, 5, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 7, 2, 1, 2, 3, 2, 1, 2, 5, 2, 3, 2, 1, 2, 7, 2, 3, 2, 5, 2, 1, 2, 3

Offset

0,5

Links

Antti Karttunen, Table of n, a(n) for n = 0..20000

Prog

(PARI) a(n) = if (n==0, 0, if (n==1, 1, if (isprime(n), 1, factor(n)[1, 1]))) \\ Michel Marcus, Jun 03 2013

Crossrefs

Cf. A020639.

Sequence in context: A082067 A082061 A327979 * A339791 A087039 A102096

Adjacent sequences: A107283 A107284 A107285 * A107287 A107288 A107289

Keyword

nonn,look

Author

Giovanni Teofilatto, May 20 2005

Status

approved