A079890 Least number > n having one more prime factor than n, not necessarily distinct.

2, 4, 4, 8, 6, 8, 9, 16, 12, 12, 14, 16, 14, 18, 18, 32, 21, 24, 21, 24, 27, 27, 25, 32, 27, 27, 36, 36, 33, 36, 33, 64, 42, 42, 42, 48, 38, 42, 42, 48, 46, 54, 46, 54, 54, 50, 49, 64, 50, 54, 52, 54, 55, 72, 63, 72, 63, 63, 62, 72, 62, 63, 81, 128, 66, 81, 69, 81, 70, 81, 74, 96

Offset: 1

Author

Reinhard Zumkeller, Jan 14 2003

Keywords

• nonn
• nice

Comments

A001222(a(n)) = A001222(n) + 1;

a(2^k) = 2^(k+1).

a(A076156(n)) = A076156(n)+1. - Reinhard Zumkeller, Feb 01 2008

Links

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

Crossrefs

Cf. A079891, A079892.

Cf. A165712.

Programs

Haskell

a079890 n = head [x | x <- [n + 1 ..], a001222 x == 1 + a001222 n]
-- Reinhard Zumkeller, Aug 29 2013

Mathematica

lng[n_]:=Module[{x=n+1,pon=PrimeOmega[n]},While[PrimeOmega[x]-pon!=1, x++]; x]; Array[lng,80] (* Harvey P. Dale, Nov 09 2011 *)