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A340037
Primes p such that (p^2+q^2)/2 and (q^2 + 2*p*q - p^2)/2 are prime, where q is the next prime after p.
1
3, 5, 13, 199, 419, 421, 1187, 1319, 1693, 1783, 2029, 2069, 2861, 3041, 3559, 3881, 4493, 4523, 4957, 5153, 6359, 7187, 7193, 8171, 8293, 8623, 8719, 8783, 9629, 10631, 12601, 13829, 13831, 15013, 15817, 16183, 16339, 17519, 18169, 18593, 18773, 18913, 19219, 19301, 19379, 19597, 20201, 20533
OFFSET
1,1
COMMENTS
p*q, (q^2-p^2)/2 and (p^2+q^2)/2 are the sides of a right triangle whose hypotenuse and sum of the other two sides are prime.
LINKS
EXAMPLE
a(3) = 13 is a term because it is prime, the next prime is 17, and (13^2+17^2)/2 = 229 and (17^2+2*13*17-13^2)/2 = 281 are prime.
MAPLE
R:= NULL: count:= 0: q:= 3:
while count < 100 do
p:= q; q:= nextprime(q);
if isprime((p^2+q^2)/2) and isprime((q^2+2*p*q-p^2)/2) then
count:= count+1; R:= R, p;
fi
od:
R;
PROG
(PARI) isok(p) = if ((p>2) && isprime(p), my(q=nextprime(p+1)); isprime((p^2+q^2)/2) && isprime((q^2 + 2*p*q - p^2)/2)) \\ Michel Marcus, Dec 27 2020
CROSSREFS
Sequence in context: A087170 A123370 A110407 * A062698 A200769 A128341
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Dec 26 2020
STATUS
approved