A091417 Integers n which are not the difference of 2 integers A and B where A is less than or equal to n such that AB+1 and AB-1 are both primes. In other words, the product A*B cannot be the middle integer of a twin prime pair.

8, 9, 10, 15, 18, 20, 30, 40, 51, 58, 60, 65, 75, 96, 100, 110, 120, 170, 195, 240, 250, 260, 315, 330, 345, 390, 540, 630, 750, 780, 910, 1020, 1720, 1890

Offset: 1

Author

William F. Sindelar (w_sindelar(AT)juno.com), Jan 05 2004

Keywords

• nonn
• fini

Comments

Sequence may be finite. Next term after 1890 if it exists must be greater than 867750.

Examples

			8 is a member: 8 is the difference between these pairs of integers: (9-1) (10-2) (11-3) (12-4) (13-5) (14-6) (15-7) (16-8). Their products (9*1) (10*2), etc. plus and minus 1 are not primes and therefore the products cannot be the middle integers of twin prime sets.
		

Crossrefs

Cf. A090695, A091182, A091183. A091418.