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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
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
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
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