A100712 Numbers n such that n*(n-1)-1 and n*(n+1)+1 are both primes.

3, 5, 6, 12, 14, 17, 20, 21, 27, 54, 57, 66, 69, 71, 77, 90, 101, 131, 141, 150, 155, 161, 164, 189, 192, 194, 231, 245, 266, 332, 336, 344, 351, 381, 392, 402, 434, 456, 476, 495, 500, 512, 531, 551, 572, 579, 582, 605, 626, 671, 677, 696, 747, 755, 762, 782, 839

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

select(n -> isprime(n*(n-1)-1) and isprime(n*(n+1)+1), [$1..1000]); # Robert Israel, Jan 04 2018

Mathematica

Select[Range[6! ], PrimeQ[ #^2-(#+1)]&&PrimeQ[ #^2+(#+1)]&] (* Vladimir Joseph Stephan Orlovsky, Dec 19 2009 *)

Crossrefs

Sequence in context: A280590 A356709 A185912 * A086187 A088082 A238961

Adjacent sequences: A100709 A100710 A100711 * A100713 A100714 A100715

Keyword

easy,nonn

Author

Pierre CAMI, Dec 10 2004

Extensions

a(54)=755 inserted by Robert Israel, Jan 04 2018

Status

approved