A130916 a(n) = smallest integer >= n which has only prime factors 2, 3 and 5.

1, 2, 3, 4, 5, 6, 8, 8, 9, 10, 12, 12, 15, 15, 15, 16, 18, 18, 20, 20, 24, 24, 24, 24, 25, 27, 27, 30, 30, 30, 32, 32, 36, 36, 36, 36, 40, 40, 40, 40, 45, 45, 45, 45, 45, 48, 48, 48, 50, 50, 54, 54, 54, 54, 60, 60, 60, 60, 60, 60, 64, 64, 64, 64, 72, 72, 72, 72, 72

Offset: 1

Author

N. J. A. Sloane, Aug 23 2009

Keywords

• nonn

Comments

This group of sequences is useful when looking for a number >= n to use as the basis for a Fast Fourier Transform when you have n data points.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A134361, A151969, A151970.

Programs

Mathematica

si[n_]:=Module[{k=n},While[Max[FactorInteger[k][[All,1]]]>5,k++];k]; Array[ si,70] (* Harvey P. Dale, Oct 14 2019 *)

R

f <- function(n) nextn(n, factors = c(2,3,5))
a <- matrix(1:256,ncol=1)
apply(a,1,f)