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A102657
Numbers k such that 11*k^2 + 11*k + 1 is prime.
0
1, 2, 5, 6, 7, 9, 11, 13, 14, 20, 23, 25, 26, 27, 28, 32, 33, 36, 37, 40, 42, 48, 49, 50, 51, 58, 61, 62, 68, 74, 75, 76, 77, 78, 81, 84, 92, 96, 103, 104, 109, 111, 119, 120, 126, 127, 133, 135, 137, 141, 142, 144, 145, 149, 153, 156, 158, 163, 166, 168, 169, 172, 176
OFFSET
1,2
EXAMPLE
For k=1, 11*k^2 + 11*k + 1 = 11*1^2 + 11*1 + 1 = 23 (prime).
For k=20, 11*k^2 + 11*k + 1 = 11*20^2 + 11*20 + 1 = 4621 (prime).
For k=40, 11*k^2 + 11*k + 1 = 11*40^2 + 11*40 + 1 = 18041 (prime).
MATHEMATICA
Select[Range[200], PrimeQ[11#^2+11#+1]&] (* Harvey P. Dale, Aug 15 2012 *)
PROG
(Magma) [n: n in [0..1000] | IsPrime(11*n^2+11*n+1)]; // Vincenzo Librandi, Nov 17 2010
(PARI) is(n)=isprime(11*n^2+11*n+1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Sequence in context: A047580 A153384 A369962 * A202115 A047324 A327184
KEYWORD
nonn,easy
AUTHOR
Parthasarathy Nambi, Feb 02 2005
STATUS
approved