1,7

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

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

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.

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

Cf. A117183, A115074.

Sequence in context: A217334 A058865 A318502 * A112295 A318973 A110517

Adjacent sequences: A115087 A115088 A115089 * A115091 A115092 A115093

nonn

Leroy Quet, Mar 01 2006

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

approved