A163620 Let q(p) be the smallest prime greater than the prime p. a(n) is the smallest integer > n that is divisible by each q(p) for all primes p dividing n.

3, 5, 6, 7, 15, 11, 9, 10, 21, 13, 15, 17, 33, 35, 18, 19, 30, 23, 21, 55, 39, 29, 30, 28, 51, 30, 33, 31, 105, 37, 33, 65, 57, 77, 45, 41, 69, 85, 42, 43, 165, 47, 78, 70, 87, 53, 60, 55, 63, 95, 102, 59, 60, 91, 66, 115, 93, 61, 105, 67, 111, 110, 66, 119, 195, 71, 114, 145

Offset

2,1

Links

Harvey P. Dale, Table of n, a(n) for n = 2..1000

Example

18 is divisible by 2 and 3. q(2) = 3, and q(3) = 5. So a(18) is the smallest integer > 18 that is divisible by both 3 and 5. Therefore a(18) = 30.

Mathematica

spf[n_]:=Module[{prs=NextPrime/@FactorInteger[n][[All, 1]], p, k=1}, p= LCM@@ prs; While[ k*p<n, k++]; k*p]; Array[spf, 70, 2]

Crossrefs

Sequence in context: A006754 A281725 A274928 * A227722 A250419 A072134

Adjacent sequences: A163617 A163618 A163619 * A163621 A163622 A163623

Keyword

nonn

Author

Leroy Quet, Aug 01 2009

Extensions

Correct second term and extend sequence Sean A. Irvine, Sep 06 2009

Status

approved