A115090 a(n) = A115074(n) - A117183(n).

0, 0, 0, 1, 0, 1, 3, 1, 0, 0, 5, 0, 1, 3, 9, 2, 1, 0, 3, 11, 1, 5, 3, 4, 0, 15, 1, 2, 17, 3, 0, 5, 9, 3, 21, 1, 5, 8, 3, 11, 1, 5, 27, 10, 3, 0, 29, 0, 5, 0, 9, 2, 15, 5, 1, 4, 35, 3, 17, 14, 11, 3, 1, 39, 5, 0, 16, 41, 2, 9, 3, 21, 45, 4, 1, 5, 9, 3, 15, 20, 11, 51, 1, 9, 5, 2, 17, 27, 11, 57, 3, 9, 0

Offset: 1

Author

Leroy Quet, Mar 01 2006

Keywords

• nonn

Comments

The union of A115090 is the complement of A007921: numbers that are not the difference of two primes. - Robert G. Wilson v, Mar 09 2006

Examples

			12, the 4th nonsquarefree positive integer, is 2^2 * 3. 3 is the largest prime dividing 12. 2 is the smallest prime dividing 12. So a(4) = 3 - 2 = 1.
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A007921, A013929, A046665, A115074, A115090, A117183.

Programs

Mathematica

(Max@# - Min@#) & /@ (First /@ FactorInteger@# & /@ Select[ Range@243, !SquareFreeQ@# &]) (* Robert G. Wilson v, Mar 09 2006 *)

Formula

a(n) = A046665(A013929(n)). - Amiram Eldar, Jan 06 2024

Extensions

More terms from Robert G. Wilson v, Mar 09 2006