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A154619
Primes of the form (4k^2 + 4k - 5)/5.
1
23, 71, 167, 191, 479, 743, 1583, 2039, 2927, 3863, 5711, 6551, 7919, 9767, 10487, 11423, 15791, 16703, 18119, 21647, 21911, 24359, 27527, 32159, 35111, 35447, 38543, 43991, 45887, 46271, 52223, 54287, 55967, 60719, 67511, 69383, 76631
OFFSET
1,1
COMMENTS
The numbers k that generate integers of the form (4k^2 + 4k - 5)/5 are in A047208. The primes are generated by the subset k = 5, 9, 14, 15, 24, 30, ... of these. - R. J. Mathar, Jan 25 2009
LINKS
MAPLE
a := proc (n) if type((4/5)*n^2+(4/5)*n-1, integer) = true and isprime((4/5)*n^2+(4/5)*n-1) = true then (4/5)*n^2+(4/5)*n-1 else end if end proc: seq(a(n), n = 1 .. 340); # Emeric Deutsch, Jan 21 2009
MATHEMATICA
Select[Table[(4n^2+4n-5)/5, {n, 3, 200}], PrimeQ] (* Vincenzo Librandi, Jul 23 2012 *)
CROSSREFS
Cf. A028880.
Sequence in context: A188831 A183012 A319052 * A142405 A139962 A248877
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jan 16 2009
EXTENSIONS
Definition corrected and more terms from R. J. Mathar and Omar E. Pol, Jan 24 2009
Extended by Emeric Deutsch, Jan 21 2009
STATUS
approved