A100576 Smallest difference between distinct prime divisors of the n-th non-prime-power.

1, 3, 1, 5, 2, 1, 3, 4, 9, 1, 11, 5, 1, 8, 15, 2, 1, 17, 10, 3, 1, 9, 2, 21, 1, 3, 14, 11, 1, 6, 5, 16, 27, 1, 29, 4, 8, 1, 15, 20, 2, 1, 35, 2, 17, 4, 1, 3, 39, 1, 12, 41, 26, 9, 1, 6, 21, 28, 45, 14, 1, 5, 8, 3, 1, 11, 2, 51, 1, 3, 34, 5, 1, 18, 27, 10, 57, 10, 1, 59, 38, 29, 1, 40, 3, 1, 12

Offset: 1

Author

Leroy Quet, Jan 02 2005

Keywords

• nonn

Examples

			6 is the first non-prime-power.
Since 6 = 2*3 and 3-2 = 1, then a(1) = 1.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Programs

Mathematica

Min[Differences[FactorInteger[#][[All,1]]]]&/@ Select[Range[ 2,150],!PrimePowerQ[ #]&] (* Harvey P. Dale, Jun 22 2021 *)

Extensions

More terms from Franklin T. Adams-Watters, Aug 29 2006