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

0,2

Links

Table of n, a(n) for n=0..11.

Example

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

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 *)

Prog

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

Crossrefs

Cf. A001221.

Sequence in context: A056245 A357338 A195886 * A147625 A157097 A349470

Adjacent sequences: A079479 A079480 A079481 * A079483 A079484 A079485

Keyword

more,nonn

Author

Jason Earls, Jan 16 2003

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

Status

approved