A228104 Numbers of form 2^(2i-1)*3^j, with i,j > 0.

6, 18, 24, 54, 72, 96, 162, 216, 288, 384, 486, 648, 864, 1152, 1458, 1536, 1944, 2592, 3456, 4374, 4608, 5832, 6144, 7776, 10368, 13122, 13824, 17496, 18432, 23328, 24576, 31104, 39366, 41472, 52488, 55296, 69984, 73728, 93312, 98304, 118098, 124416, 157464, 165888

Offset: 1

Author

Ralf Stephan, Aug 10 2013

Keywords

• nonn
• easy

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Subsequence of A033845 and A011775.

Programs

Maple

N:= 10^6: # for terms <= N
sort([seq(seq(2^i * 3^j, j = 1 .. ilog[3](N/2^i)),i=1..ilog2(N/3),2)]); # Robert Israel, Oct 14 2024

Mathematica

With[{max = 2*10^5}, Flatten[Table[2^(2*i-1)*3^j, {i, 1, (Log2[max]+1)/2}, {j, 1, Log[3, max/2^(2*i-1)]}]] // Sort] (* Amiram Eldar, Mar 29 2025 *)

PARI

vecsort(vector(10000,n,2^(2*((n-1)%100)+1)*3^((n\100)+1))) /* (first 100 values) */

Formula

Sum_{n>=1} 1/a(n) = 1/3. - Amiram Eldar, Mar 29 2025