

A073337


Primes of the form 4*k^2  10*k + 7 with k positive.


11



3, 13, 31, 241, 307, 463, 757, 1123, 1723, 3307, 3541, 4831, 5113, 5701, 6007, 8011, 9901, 10303, 11131, 12433, 13807, 14281, 17293, 20023, 20593, 21757, 23563, 24181, 26083, 28057, 30103, 35911, 41413, 43891, 46441, 53593, 60271, 78121, 82657, 86143, 95791, 108571, 123553, 127807, 136531, 145543, 147073, 156421
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OFFSET

1,1


COMMENTS

Primes of the form k^2 + k + 1 with k odd and positive.  Peter Munn, Jan 27 2018


LINKS



EXAMPLE

3 is a term because for k=2, 4*k^2  10*k + 7 = 3 a prime.
7 is not a term because 7 can only be obtained with k=0 or k=5/2.


MAPLE

select(isprime, [seq(4*n^210*n+7 , n=2..300)]); # Muniru A Asiru, Apr 15 2018


MATHEMATICA

Select[Table[4 n^2  10 n + 7, {n, 1, 200}], PrimeQ] (* Vincenzo Librandi, Dec 23 2019 *)


PROG

(PARI) select(isprime, vector(300, k, 4*k^2  10*k + 7)) \\ Joerg Arndt, Feb 28 2018
(GAP) Filtered(List([2..300], n>4*n^210*n+7), IsPrime); # Muniru A Asiru, Apr 15 2018
(Magma) [a: n in [1..400]  IsPrime(a) where a is 4*n^2  10*n + 7]; // Vincenzo Librandi, Dec 23 2019


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



EXTENSIONS

a(1)=7 inserted and typo in Mathematica code corrected by Vincenzo Librandi, Dec 09 2011


STATUS

approved



