A115024 Natural numbers n such that the number of prime factors of n (counted with multiplicity) is equal to the number of decimal digits of n.

2, 3, 5, 7, 10, 14, 15, 21, 22, 25, 26, 33, 34, 35, 38, 39, 46, 49, 51, 55, 57, 58, 62, 65, 69, 74, 77, 82, 85, 86, 87, 91, 93, 94, 95, 102, 105, 110, 114, 116, 117, 124, 125, 130, 138, 147, 148, 153, 154, 164, 165, 170, 171, 172, 174, 175, 182, 186, 188, 190, 195

Offset: 1

Author

Giovanni Teofilatto, Feb 24 2006

Keywords

• base
• easy
• nonn

Examples

			25 = 5*5 and 25 has two digits.
116 = 2*2*29 and 116 has three digits.
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A165256, A167050.

Programs

Mathematica

Select[Range[2, 300], Sum[FactorInteger[ # ][[i]][[2]], {i, 1, Length[FactorInteger[ # ]]}] == Floor[Log[10, # ] + 1] &] (* Stefan Steinerberger, Feb 27 2006 *)
Select[Range[200],PrimeOmega[#]==IntegerLength[#]&] (* Harvey P. Dale, Jul 28 2020 *)

PARI

is(n)=#Str(n)==bigomega(n) \\ Charles R Greathouse IV, Feb 04 2013

Extensions

More terms from Stefan Steinerberger, Feb 27 2006