A036335 Total number of composite numbers with n digits and n prime factors (counted with multiplicity).

0, 31, 225, 1563, 10222, 63030, 374264, 2160300, 12196405, 67724342, 371233523, 2014305995

Offset: 1

Author

Patrick De Geest, Dec 15 1998

Keywords

• nonn
• base
• more

Comments

Essentially the same as A124033.

Examples

			a(1) = 0, since any single-digit number with 1 prime factor is a prime!
		

Links

• Carlos Rivera, Puzzle 25. Composed primes (by G.L. Honaker, Jr.), The Prime Puzzles and Problems Connection. (A related puzzle.)

Crossrefs

Cf. A036336, A036337, A036338.

Programs

Mathematica

Table[Total[Table[If[CompositeQ[n]&&PrimeOmega[n]==x,1,0],{n,10^(x-1),10^x-1}]],{x,8}] (* The program generates the first 8 terms of the sequence. *) (* Harvey P. Dale, Jun 19 2022 *)

Extensions

One more term from Naohiro Nomoto, Jul 31 2001

a(9)-a(12) from Ray Chandler, Apr 12 2011