A118290 a(1) = 1. a(n) = number of terms among the sequence's first (n-1) terms which are divisible by the smallest prime dividing a(n-1), or which are divisible by 1 if a(n-1)= 1.

1, 1, 2, 1, 4, 2, 3, 1, 8, 4, 5, 1, 12, 6, 7, 1, 16, 8, 9, 4, 10, 11, 1, 23, 1, 25, 3, 5, 4, 12, 13, 1, 32, 14, 15, 7, 3, 8, 16, 17, 1, 41, 1, 43, 1, 45, 9, 10, 18, 19, 1, 51, 12, 20, 21, 14, 22, 23, 2, 24, 25, 9, 16, 26, 27, 17, 3, 18, 28, 29, 1, 71, 1, 73, 1, 75, 20, 30, 31

Offset

1,3

Comments

If a(n-1) = 1, then a(n) = n-1, obviously.

Links

Diana Mecum, Table of n, a(n) for n = 1..200

Example

a(13)= 12. So a(14) = the number of terms among the first 13 terms which are divisible by the lowest prime dividing 12 (which is 2).
a(3)=2, a(5)=4, a(6)=2, a(9)=8, a(10)=4 and a(13) = 12 are the six terms each divisible by 2, so a(14) = 6.

Crossrefs

Cf. A118291.

Sequence in context: A269370 A123755 A118291 * A208569 A341392 A351886

Adjacent sequences: A118287 A118288 A118289 * A118291 A118292 A118293

Keyword

nonn

Author

Leroy Quet, Apr 22 2006

Extensions

More terms from Diana L. Mecum, May 29 2007

Status

approved