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A162471 Prime divisors of {n^2+n+1} which do not occur in that sequence. See A002383. 3
19, 37, 61, 67, 79, 97, 103, 109, 127, 139, 151, 163, 181, 193, 199 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

19 divides n^2+n+1 for n = 7, 11, 26, 30 ,..., etc. The first pair of first differences of multiples of 19 sum to 19, a pattern which holds for all prime divisors of n^2+n+1 (conjecture) except for 3 (every third element of {n^2+n+1} is divisible by 3).

LINKS

Table of n, a(n) for n=1..15.

EXAMPLE

The first prime divisor of {n^2+n+1} which is not an element of the sequence A002383 is 19. 7^2+7+1 = 57 = 19*3.

CROSSREFS

A002383

Sequence in context: A161705 A131600 A175546 * A124268 A259648 A154944

Adjacent sequences:  A162468 A162469 A162470 * A162472 A162473 A162474

KEYWORD

nonn

AUTHOR

Daniel Tisdale, Jul 04 2009

STATUS

approved

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Last modified March 25 01:17 EDT 2019. Contains 321450 sequences. (Running on oeis4.)