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A134361 revision #10

A134361

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

1, 2, 3, 4, 6, 6, 8, 8, 9, 12, 12, 12, 16, 16, 16, 16, 18, 18, 24, 24, 24, 24, 24, 24, 27, 27, 27, 32, 32, 32, 32, 32, 36, 36, 36, 36, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 54, 54, 54, 54, 54, 54, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 72, 72, 72, 72, 72, 72, 72, 72

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Can be used, for example, to derive A084788 and A084790 from A084789. - Charles R Greathouse IV, Jul 09 2021

LINKS

Table of n, a(n) for n=1..72.

MATHEMATICA

With[{pf23=Union[Flatten[Table[Times@@@Tuples[{2, 3}, n], {n, 0, 6}]]]}, Flatten[Table[Select[pf23, #>=n&, 1], {n, 80}]]] (* Harvey P. Dale, Mar 07 2012 *)

PROG

(R) f <- function(n) nextn(n, factors = c(2, 3))

a <- matrix(1:256, ncol=1)

apply(a, 1, f)

(PARI) a(n)=my(v=List()); for(i=0, logint(n, 3)+1, my(t=3^i); t<<=if(t>n, 0, exponent(n\t)+1); listput(v, t)); Set(v)[1] \\ Charles R Greathouse IV, Jul 09 2021

CROSSREFS

Cf. A130916, A134361, A151969.

Sequence in context: A367964 A214965 A350786 * A142727 A347388 A112275

Adjacent sequences: A134358 A134359 A134360 * A134362 A134363 A134364

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Aug 23 2009; corrected Mar 07 2012

STATUS

approved