

A125602


Prime centered triangular numbers.


5



19, 31, 109, 199, 409, 571, 631, 829, 1489, 1999, 2341, 2971, 3529, 4621, 4789, 7039, 7669, 8779, 9721, 10459, 10711, 13681, 14851, 16069, 16381, 17659, 20011, 20359, 23251, 25939, 27541, 29191, 29611, 31321, 34429, 36739, 40099, 40591, 42589
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OFFSET

1,1


COMMENTS

Or prime terms in A005448, or primes of the form 3n(n1)/2 + 1.


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000


MATHEMATICA

lst={}; Do[If[PrimeQ[p=3n(n1)/2+1], (*Print[p]; *)AppendTo[lst, p]], {n, 10^3}]; lst [From Vladimir Joseph Stephan Orlovsky, Aug 21 2008]


PROG

(MAGMA) [a: n in [0..200]  IsPrime(a) where a is (3*n^2  3*n + 2) div 2]; // Vincenzo Librandi, Mar 22 2013


CROSSREFS

Cf. A005448, A125603.
Sequence in context: A243450 A237418 A240126 * A139847 A087764 A146691
Adjacent sequences: A125599 A125600 A125601 * A125603 A125604 A125605


KEYWORD

nonn,easy


AUTHOR

Zak Seidov, Nov 27 2006


STATUS

approved



