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A079141 Primes of the form p^2 + 6 where p is prime. 4
31, 127, 367, 967, 3727, 6247, 7927, 11887, 17167, 22807, 39607, 72367, 109567, 160807, 185767, 323767, 502687, 737887, 863047, 885487, 942847, 982087, 1079527, 1560007, 1739767, 1852327, 1985287, 2105407, 2343967, 2399407 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Sum of reciprocals = 0.0447155381... [4 additional digits from Jon E. Schoenfield, Jan 15 2015]

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

MATHEMATICA

f[n_]:=n^2+6; lst={}; Do[p=Prime[n]; If[PrimeQ[f[p]], AppendTo[lst, f[p]]], {n, 7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jul 17 2009 *)

Select[#^2+6&/@Prime[Range[300]], PrimeQ] (* Harvey P. Dale, Nov 16 2012 *)

PROG

(PARI) sqppn(n) = {sr=0; forprime(x=3, n, y = x*x+6; if(isprime(y), print1(y" "); sr+=1.0/y; ); ); print(); print(sr); } \\ Primes of the form p^2 + 6 and the sum of the reciprocals.

CROSSREFS

Cf. A056909.

Sequence in context: A127578 A333245 A158563 * A049203 A065403 A278054

Adjacent sequences:  A079138 A079139 A079140 * A079142 A079143 A079144

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Dec 26 2002

STATUS

approved

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Last modified April 16 18:53 EDT 2021. Contains 343050 sequences. (Running on oeis4.)