A025618 Numbers of form 4^i*6^j, with i, j >= 0.

1, 4, 6, 16, 24, 36, 64, 96, 144, 216, 256, 384, 576, 864, 1024, 1296, 1536, 2304, 3456, 4096, 5184, 6144, 7776, 9216, 13824, 16384, 20736, 24576, 31104, 36864, 46656, 55296, 65536, 82944, 98304, 124416, 147456, 186624, 221184, 262144, 279936

Offset: 1

Author

David W. Wilson

Keywords

• easy
• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Subsequence of A003586.

Programs

Mathematica

f[upto_]:=Module[{max4=Floor[Log[upto]/Log[4]],max6 = Floor[ Log[ upto]/ Log[6]], seq},seq=Union[4^First[#] 6^Last[#]&/@Tuples[ {Range[ 0,max4],Range[ 0,max6]}]];Select[seq,#<=upto&]];f[300000]  (* Harvey P. Dale, Mar 05 2011 *)

Formula

Sum_{n>=1} 1/a(n) = (4*6)/((4-1)*(6-1)) = 8/5. - Amiram Eldar, Sep 24 2020

a(n) ~ exp(sqrt(2*log(4)*log(6)*n)) / sqrt(24). - Vaclav Kotesovec, Sep 24 2020

a(n) = 4^A025647(n) * 6^A025658(n). - R. J. Mathar, Jul 06 2025