A091417 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

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

LINKS

Table of n, a(n) for n=1..34.

EXAMPLE

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.

Sequence in context: A046415 A358674 A358675 * A069237 A334728 A070480

Adjacent sequences: A091414 A091415 A091416 * A091418 A091419 A091420

KEYWORD

nonn,fini

AUTHOR

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

STATUS

approved