A133304 Number of distinct prime factors of A101291.

2, 3, 5, 5, 5, 6, 5, 5, 5, 4, 5, 4, 5, 7, 7, 6, 5, 4, 5, 9, 7, 5, 4, 5, 6, 6, 8, 5, 6, 4, 7, 5, 7, 5, 5, 7, 4, 4, 6, 7, 6, 7, 8, 5, 8, 7, 6, 5, 7, 7, 6, 7, 4, 5, 8, 7, 8, 8, 7, 6

Offset: 1

Author

Parthasarathy Nambi, Oct 18 2007

Keywords

• nonn
• base

Examples

			The number of distinct prime factors of 45 is 2.
The number of distinct prime factors of 4905 is 3.
The number of distinct prime factors of 494550 is 5.
		

Links

• Dario Alpern, Factorization using the Elliptic Curve Method.

Crossrefs

Cf. A101291.

Programs

Maple

A101291 := proc(n) 99*100^n/200-9*10^n/20 ; end: A133304 := proc(n) nops(numtheory[factorset](A101291(n))) ; end: for n from 1 do printf("%d,\n",A133304(n)) ; od: # R. J. Mathar, Jul 08 2009

Mathematica

f[n_] := 10^n(10^n - 1)/2; Table[PrimeNu[f[n] - f[n - 1]], {n, 60}] (* James C. McMahon, Mar 14 2025 *)

Extensions

28 more terms from R. J. Mathar, Jul 08 2009

a(41)-a(60) from James C. McMahon, Mar 14 2025