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A120395 Let p(1) = 13. Then a(n) is the least k such that p(n+1) = (k*p(n))^2 + k*p(n) - 1 is prime. 4
1, 1, 4, 4, 10, 1, 351, 240, 620, 1362, 2184, 46, 2944 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

p sequence starts 181, 32941, 17361883459, 4822959955971812408731, ...

a(13) corresponds to a 12,272-digit BPSW-probable prime. - Charles R Greathouse IV, Apr 22 2012

LINKS

Table of n, a(n) for n=1..13.

PROG

(PARI) p=13; for(i=1, 9, k=1; while(!ispseudoprime(t=(k*p)^2+k*p-1), k++); p=t; print1(k", ")) \\ Charles R Greathouse IV, Apr 20 2012

CROSSREFS

Sequence in context: A091016 A198025 A205549 * A321078 A160723 A255486

Adjacent sequences:  A120392 A120393 A120394 * A120396 A120397 A120398

KEYWORD

nonn

AUTHOR

Pierre CAMI, Jul 01 2006

EXTENSIONS

a(9)-a(12) from Charles R Greathouse IV, Apr 20 2012

a(13) from Charles R Greathouse IV, Apr 22 2012

STATUS

approved

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Last modified November 30 09:34 EST 2021. Contains 349419 sequences. (Running on oeis4.)