A079482 Smallest number k such that k and k+1 have n and n+1 distinct prime divisors.

1, 5, 65, 1364, 40754, 1774409, 58524465, 5327923964, 555409903685, 70367042561529, 5819629108725509, 567969628457303709

Offset: 0

Author

Jason Earls, Jan 16 2003

Keywords

• more
• nonn

Examples

			a(3) = 1364 because 1364 has 3 and 1365 has 4 distinct prime divisors.
		

Crossrefs

Cf. A001221.

Programs

Mathematica

a[n_] := Module[{k = 1}, While[PrimeNu[k] != n || PrimeNu[k + 1] != n + 1, k++]; k]; Array[a, 10, 0] (* Amiram Eldar, Dec 03 2018 *)

PARI

for(n=1,10,k=1; while(omega(k)!=n || omega(k+1)!=n+1,k++); print1(k","))

Extensions

a(6) from Ryan Propper, Jul 21 2006

a(7)-a(8) from Donovan Johnson, Apr 05 2008

a(9)-a(11) from Donovan Johnson, Feb 04 2009

a(0)=1 preprended by Rémy Sigrist, Dec 03 2018