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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
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
Sequence in context: A102872 A102873 A356847 * A158892 A106022 A279795
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Mar 14 2021
STATUS
approved

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Last modified March 1 20:05 EST 2024. Contains 370443 sequences. (Running on oeis4.)