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A084952 Middle q of three consecutive primes p,q,r such that (p^2 + q^2 + r^2)/3 is prime. 2
11, 13, 23, 43, 53, 103, 211, 223, 233, 263, 271, 281, 293, 317, 331, 349, 397, 431, 463, 479, 499, 557, 577, 643, 761, 773, 787, 797, 829, 929, 1187, 1327, 1373, 1399, 1427, 1429, 1451, 1453, 1483, 1583, 1627, 1667, 1693, 1747, 1753, 1783, 2027, 2099, 2129 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

a(3)=23 because (19^2 + 23^2 + 29^2)/3 = 1731/3 = 577 is prime.

MAPLE

q:= 5: r:= 7:

Res:= NULL: count:= 0:

while count < 100 do

  p:= q;

  q:= r;

  r:= nextprime(r);

  if isprime((p^2+q^2+r^2)/3) then count:= count+1; Res:= Res, q fi

od:

Res; # Robert Israel, Aug 20 2018

CROSSREFS

Cf. A075893, A084951.

Sequence in context: A097933 A166484 A127043 * A277048 A275598 A090433

Adjacent sequences:  A084949 A084950 A084951 * A084953 A084954 A084955

KEYWORD

easy,nonn

AUTHOR

Hugo Pfoertner, Jun 14 2003

STATUS

approved

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Last modified January 28 06:29 EST 2020. Contains 331317 sequences. (Running on oeis4.)