A165713 a(n) = the smallest integer > n that is divisible by exactly the same number of distinct primes as n is.

3, 4, 5, 7, 10, 8, 9, 11, 12, 13, 14, 16, 15, 18, 17, 19, 20, 23, 21, 22, 24, 25, 26, 27, 28, 29, 33, 31, 42, 32, 37, 34, 35, 36, 38, 41, 39, 40, 44, 43, 60, 47, 45, 46, 48, 49, 50, 53, 51, 52, 54, 59, 55, 56, 57, 58, 62, 61, 66, 64, 63, 65, 67, 68, 70, 71, 69, 72, 78, 73, 74

Offset

2,1

Links

Reinhard Zumkeller, Table of n, a(n) for n = 2..10000

Example

12 = 2^2 *3, and so is divisible by exactly 2 distinct primes. The next larger number divisible by exactly 2 distinct primes is 14, which is 2*7. So a(12) = 14.

Mathematica

a[n_] := For[nu = PrimeNu[n]; k = n+1, True, k++, If[PrimeNu[k] == nu, Return[k]]]; Table[a[n], {n, 2, 100}] (* Jean-François Alcover, Nov 18 2013 *)

Prog

(Haskell)
a165713 n = head [x | x <- [n + 1 ..], a001221 x == a001221 n]
-- Reinhard Zumkeller, Aug 29 2013

Crossrefs

Cf. A165712, A137929.

Cf. A001221, A079892.

Sequence in context: A000702 A067526 A101760 * A105148 A370862 A072556

Adjacent sequences: A165710 A165711 A165712 * A165714 A165715 A165716

Keyword

nonn

Author

Leroy Quet, Sep 24 2009

Extensions

More terms from Sean A. Irvine, Feb 10 2010

Status

approved