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A130916
a(n) = smallest integer >= n which has only prime factors 2, 3 and 5.
4
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
1,2
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
MATHEMATICA
si[n_]:=Module[{k=n}, While[Max[FactorInteger[k][[All, 1]]]>5, k++]; k]; Array[ si, 70] (* Harvey P. Dale, Oct 14 2019 *)
PROG
(R) f <- function(n) nextn(n, factors = c(2, 3, 5))
a <- matrix(1:256, ncol=1)
apply(a, 1, f)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Aug 23 2009
STATUS
approved