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A163579 Primes of the form floor(k*(k+1)*Pi/2), k>=0, where Pi = 3.1415.. = A000796. 2
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 (list; graph; refs; listen; history; text; internal format)
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 A238663 A141966

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

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Last modified March 5 11:27 EST 2021. Contains 341823 sequences. (Running on oeis4.)