A071929 Numbers k such that the sum of exponents of k is equal to the greatest prime factor of k; a(1)=1.

1, 4, 12, 18, 27, 80, 120, 180, 200, 270, 300, 405, 448, 450, 500, 672, 675, 750, 1008, 1120, 1125, 1250, 1512, 1568, 1680, 1875, 2268, 2352, 2520, 2800, 3125, 3402, 3528, 3780, 3920, 4200, 5103, 5292, 5488, 5670, 5880, 6300, 7000, 7938, 8232, 8505, 8820

Offset: 1

Author

Jason Earls, Jun 14 2002

Keywords

• nonn

Examples

			28160 is a term since 28160 = 2^9*5^1*11^1 and 9+1+1 = 11 and Gpf(28160) = 11.
		

Links

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

Crossrefs

Cf. A006530, A086436.

Programs

Mathematica

Select[Range[10^4], (f = FactorInteger[#])[[-1, 1]] == Plus @@ f[[;;,2]] &] (* Amiram Eldar, Dec 08 2019 *)