A108771 Numbers of the form (12^i)*(13^j), with i, j >= 0.

1, 12, 13, 144, 156, 169, 1728, 1872, 2028, 2197, 20736, 22464, 24336, 26364, 28561, 248832, 269568, 292032, 316368, 342732, 371293, 2985984, 3234816, 3504384, 3796416, 4112784, 4455516, 4826809, 35831808, 38817792, 42052608, 45556992

Offset: 1

Author

Douglas Winston (douglas.winston(AT)srupc.com), Jun 25 2005

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A107326, A107364, A107462, A107466, A107710, A108056, A107764, A108748, A108761, A108090.

Programs

Maple

N:= 10^8: # to get all terms <= N
sort([seq(seq(12^i*13^j, j = 0 .. floor(log[13](N/12^i))), i=0..floor(log[12](N)))]); # Robert Israel, Jun 16 2019

Mathematica

With[{max = 5*10^7}, Flatten[Table[12^i*13^j, {i, 0, Log[12, max]}, {j, 0, Log[13, max/12^i]}]] // Sort] (* Amiram Eldar, Mar 29 2025 *)

Formula

Sum_{n>=1} 1/a(n) = 13/11. - Amiram Eldar, Mar 29 2025