A091376 Numbers k with property that the number of prime factors of k (counted with repetition) equals the smallest prime factor of k.

4, 6, 10, 14, 22, 26, 27, 34, 38, 45, 46, 58, 62, 63, 74, 75, 82, 86, 94, 99, 105, 106, 117, 118, 122, 134, 142, 146, 147, 153, 158, 165, 166, 171, 178, 194, 195, 202, 206, 207, 214, 218, 226, 231, 254, 255, 261, 262, 273, 274, 278, 279, 285, 298, 302, 314

Offset: 1

Author

Reinhard Zumkeller, Jan 04 2004

Keywords

• nonn

Comments

A091371(a(n)) = 0: A001222(a(n))=A020639(a(n)).

Prime factors counted with multiplicity. - Harvey P. Dale, Nov 11 2012

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A091373, A091375, A091377.

Cf. A002808.

Cf. A100484 (subsequence).

Programs

Haskell

a091376 n = a091376_list !! (n-1)
a091376_list = [x | x <- a002808_list, a001222 x == a020639 x]
-- Reinhard Zumkeller, Nov 11 2012

Mathematica

pfQ[n_]:=Module[{fi=Transpose[FactorInteger[n]]},fi[[1,1]] == Total[Last[fi]]]; Rest[Select[Range[400],pfQ]] (* Harvey P. Dale, Nov 11 2012 *)
Select[Range[400],PrimeOmega[#]==FactorInteger[#][[1,1]]&] (* Harvey P. Dale, Nov 26 2024 *)

Extensions

Definition edited by N. J. A. Sloane, Jan 21 2020