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A342506 Primes p such that (p*s+q*r)/2 is prime, where p,q,r,s are consecutive primes. 4
5, 7, 13, 97, 107, 157, 223, 311, 353, 419, 479, 541, 673, 691, 701, 839, 877, 1049, 1193, 1297, 1423, 1559, 1747, 1787, 2017, 2239, 2341, 2383, 2459, 2633, 2719, 2797, 2833, 2851, 3121, 3209, 3359, 3391, 3581, 3613, 3617, 3671, 4219, 4261, 4729, 4831, 4933, 4993, 5023, 5309, 5393, 5657, 5867 (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) = 13 is a term because 13, 17, 19, 23 are consecutive primes with (13*23+17*19)/2 = 311 prime.

MAPLE

R:= NULL: count:= 0:

q:= 3: r:= 5: s:= 7:

while count < 100 do

  p:= q; q:= r; r:= s; s:= nextprime(s);

  if isprime((p*s+q*r)/2) then

     count:= count+1; R:= R, p;

  fi

od:

R;

CROSSREFS

Cf. A342504, A342508.

Sequence in context: A077781 A102872 A102873 * A158892 A106022 A279795

Adjacent sequences:  A342503 A342504 A342505 * A342507 A342508 A342509

KEYWORD

nonn

AUTHOR

J. M. Bergot and Robert Israel, Mar 14 2021

STATUS

approved

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Last modified October 28 12:43 EDT 2021. Contains 348329 sequences. (Running on oeis4.)