A268063 Primes of the form (k^3 - k^2 - k - 1)/2 for some integer k > 0.

7, 47, 599, 1567, 5807, 7487, 9463, 20807, 24623, 28879, 33599, 81647, 111599, 123007, 161839, 225263, 262399, 282407, 397807, 541007, 573247, 606743, 641519, 922807, 1115399, 1513727, 1577383, 1709999, 1779007, 1849847, 1997119, 2399039, 2573807, 2948399

Offset

1,1

Comments

Also primes of the form 4*k^3 + 4*k^2 - 1.

Links

G. C. Greubel, Table of n, a(n) for n = 1..3240

Example

k=15: (15^3 - 15^2 - 15 - 1)/2 = 1567 (is prime).

Mathematica

Select[Table[(n^3 - n^2 - n - 1) / 2, {n, 200}], PrimeQ] (* Vincenzo Librandi, Jan 26 2016 *)

Prog

(Sage) [(k^3-k^2-k-1)/2 for k in [2*i+1 for i in [1..100]] if is_prime(Integer((k^3-k^2-k-1)/2))] # Tom Edgar, Jan 25 2016
(Magma) [a: n in [0..200] | IsPrime(a) where a is (n^3-n^2-n-1) div 2 ]; // Vincenzo Librandi, Jan 26 2016
(PARI) lista(nn) = for(n=1, nn, if(ispseudoprime(p=4*n^3+4*n^2-1), print1(p, ", "))); \\ Altug Alkan, Mar 14 2016

Crossrefs

Cf. A004771, A042991, A168489.

Sequence in context: A006873 A228695 A368295 * A015097 A341213 A201176

Adjacent sequences: A268060 A268061 A268062 * A268064 A268065 A268066

Keyword

nonn,easy

Author

Emre APARI, Jan 25 2016

Extensions

More terms from Tom Edgar, Jan 25 2016

Status

approved