A163579 Primes of the form floor(k*(k+1)*Pi/2), k>=0, where Pi = 3.1415.. = A000796.

3, 31, 47, 113, 659, 1021, 1187, 1979, 2971, 3251, 5749, 9679, 10433, 14627, 20593, 22807, 23957, 35107, 39461, 55813, 58207, 109063, 152417, 157349, 201881, 227419, 244463, 262121, 292469, 295187, 310357, 318793, 320209, 323053, 328777, 333103

Offset

1,1

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Mathematica

s=0; lst={}; Do[s+=n; p=IntegerPart[s]; If[PrimeQ[p], AppendTo[lst, p]], {n, 0, 7!, Pi}]; lst
Select[Floor[Accumulate[Range[800]]*Pi], PrimeQ] (* Harvey P. Dale, Nov 20 2018 *)

Prog

(PARI) for(n=1, 500, m=floor(n*(n+1)*Pi/2); if(isprime(m), print1(m, ", "))) \\ G. C. Greubel, Jul 28 2017

Crossrefs

Sequence in context: A107210 A256473 A119739 * A290401 A341928 A238663

Adjacent sequences: A163576 A163577 A163578 * A163580 A163581 A163582

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Jul 31 2009

Extensions

Definition clarified by R. J. Mathar, Sep 24 2011

Status

approved