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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 (list; graph; refs; listen; history; text; internal format)
 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 Vincenzo Librandi, Table of n, a(n) for n = 1..1000 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 Adjacent sequences: A154616 A154617 A154618 * A154620 A154621 A154622 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

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Last modified December 4 01:10 EST 2023. Contains 367541 sequences. (Running on oeis4.)