A100573 Smallest difference between distinct prime divisors of n, or 0 if n is a prime power.

0, 0, 0, 0, 0, 1, 0, 0, 0, 3, 0, 1, 0, 5, 2, 0, 0, 1, 0, 3, 4, 9, 0, 1, 0, 11, 0, 5, 0, 1, 0, 0, 8, 15, 2, 1, 0, 17, 10, 3, 0, 1, 0, 9, 2, 21, 0, 1, 0, 3, 14, 11, 0, 1, 6, 5, 16, 27, 0, 1, 0, 29, 4, 0, 8, 1, 0, 15, 20, 2, 0, 1, 0, 35, 2, 17, 4, 1, 0, 3, 0, 39, 0, 1, 12, 41, 26, 9, 0, 1, 6, 21, 28, 45

Offset: 1

Author

Leroy Quet, Jan 02 2005

Keywords

• nonn

Examples

			For 30 = 2*3*5, 2 and 3 are separated by only 1, so a(30) = 1.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537

Crossrefs

Cf. also A046665, A297173.

Programs

Mathematica

<Labos Elemer, Jan 05 2005 *)
Table[Min[Differences[Transpose[FactorInteger[n]][[1]]]],{n,100}]/.\[Infinity]->0 (* Harvey P. Dale, Jul 27 2015 *)

PARI

A100573(n) = if(omega(n)<=1,0,my(ps=factor(n)[,1]); vecmin(vector((#ps)-1,i,ps[i+1]-ps[i]))); \\ Antti Karttunen, Mar 03 2018

Extensions

More terms from Labos Elemer, Jan 05 2005