A165713 - OEIS

%I #13 Mar 11 2014 01:32:48

%S 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,

%T 29,33,31,42,32,37,34,35,36,38,41,39,40,44,43,60,47,45,46,48,49,50,53,

%U 51,52,54,59,55,56,57,58,62,61,66,64,63,65,67,68,70,71,69,72,78,73,74

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

%H Reinhard Zumkeller, <a href="/A165713/b165713.txt">Table of n, a(n) for n = 2..10000</a>

%e 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.

%t 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 *)

%o (Haskell)

%o a165713 n = head [x | x <- [n + 1 ..], a001221 x == a001221 n]

%o -- _Reinhard Zumkeller_, Aug 29 2013

%Y Cf. A165712, A137929.

%Y Cf. A001221, A079892.

%K nonn

%O 2,1

%A _Leroy Quet_, Sep 24 2009

%E More terms from _Sean A. Irvine_, Feb 10 2010