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A340126 Primes p1 such that, with p2, p3, p4 the next three primes, p1*p2+p3*p4+p1, p1*p2+p3*p4+p2, p1*p2+p3*p4+p3 and p1*p2+p3*p4+p4 are all prime. 1
61751, 79393, 754991, 768373, 934393, 999529, 1575031, 1666019, 2512561, 3158069, 3434089, 3658607, 3815641, 3883967, 4063547, 4161721, 4390489, 5009737, 5539949, 5701019, 6475223, 6604691, 6736297, 7164757, 8194651, 8395997, 8440331, 9755821, 10003223 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
a(1) = 61751 is a term because with p1 = 61751, p2 = 61757, p3 = 61781, p4 = 61813, we have p1*p2+p3*p4+p1 = 7632487211, p1*p2+p3*p4+p2 = 7632487217, p1*p2+p3*p4+p3 = 7632487241, p1*p2+p3*p4+p4 = 7632487273, all primes.
MAPLE
p2:=2: p3:= 3: p4:= 5: count:= 0: R:= NULL:
while count < 10 do
p1:= p2; p2:= p3; p3:= p4; p4:= nextprime(p4);
w:= p1*p2+p3*p4;
if andmap(t -> isprime(t+w), [p1, p2, p3, p4]) then
count:= count+1; R:= R, p1
fi
od:
R;
CROSSREFS
Sequence in context: A340438 A253613 A257749 * A112015 A234864 A128879
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Dec 29 2020
EXTENSIONS
a(11)-a(29) from Jon E. Schoenfield, Dec 29 2020
STATUS
approved

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Last modified March 28 05:39 EDT 2024. Contains 371235 sequences. (Running on oeis4.)