A108201 Numbers of the form (5^i)*(12^j), with i, j >= 0.

1, 5, 12, 25, 60, 125, 144, 300, 625, 720, 1500, 1728, 3125, 3600, 7500, 8640, 15625, 18000, 20736, 37500, 43200, 78125, 90000, 103680, 187500, 216000, 248832, 390625, 450000, 518400, 937500, 1080000, 1244160, 1953125, 2250000, 2592000

Offset: 1

Author

Douglas Winston (douglas.winston(AT)srupc.com), Jun 15 2005

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A025622, A003595, A025623, A025624, A025625, A003598, A107466, A064476.

Programs

Mathematica

Take[Union[5^First[#] 12^Last[#]&/@Tuples[Range[0,20],2]],50] (* Harvey P. Dale, Mar 23 2012 *)

Formula

Sum_{n>=1} 1/a(n) = 15/11. - Amiram Eldar, Mar 29 2025