A025615 Numbers of form 3^i*8^j, with i, j >= 0.

1, 3, 8, 9, 24, 27, 64, 72, 81, 192, 216, 243, 512, 576, 648, 729, 1536, 1728, 1944, 2187, 4096, 4608, 5184, 5832, 6561, 12288, 13824, 15552, 17496, 19683, 32768, 36864, 41472, 46656, 52488, 59049, 98304, 110592, 124416, 139968, 157464, 177147, 262144

Offset

1,2

Comments

Subset of A003586 3-smooth numbers: numbers of the form 2^i*3^j with i, j >= 0. - Daniel Forgues, Feb 24 2011

Indices for which a term is a power of 3 are in A025699 and a power of 8 are in A025728- Bernard Schott, Dec 27 2021

Links

Georg Fischer, Table of n, a(n) for n = 1..300

Formula

Sum_{n>=1} 1/a(n) = 12/7. - Amiram Eldar, Feb 18 2021

From Bernard Schott, Dec 27 2021: (Start)

a(A025699(n)) = 3^(n-1).

a(A025728(n)) = 8^(n-1). (End)

Mathematica

lim = 262144; Select[Sort[Flatten[Table[3^i 8^j, {i, 0, Log[3, lim]}, {j, 0, Log[8, lim]}]]], # <=lim &] (* T. D. Noe, Mar 01 2012 *)

Prog

(PARI) list(lim)=my(v=List(), N); for(n=0, logint(lim\=1, 3), N=3^n; while(N<=lim, listput(v, N); N<<=3)); Set(v) \\ Charles R Greathouse IV, Jan 10 2018

Crossrefs

Cf. A003586, A025699, A025728.

Sequence in context: A176205 A099256 A167344 * A297324 A223331 A101720

Adjacent sequences: A025612 A025613 A025614 * A025616 A025617 A025618

Keyword

easy,nonn

Author

David W. Wilson

Status

approved