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A242366 Primes p such that p1 = ceil(p/2) + p is prime and p2 = floor(p1/2) + p is prime. 2
2, 3, 11, 59, 131, 179, 347, 1259, 1571, 1979, 2027, 2411, 2699, 2819, 3251, 3347, 4211, 5051, 5099, 5171, 5531, 6779, 7187, 8747, 10091, 12227, 13259, 13451, 13499, 13931, 14411, 14771, 15131, 15467, 16451, 16691, 17987, 18131, 18539, 18731, 18899, 19211 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms after 2 are congruent to 3 mod 8, as this is needed for p, p1 and p2 to be odd.  If p = 3 + 8*k, then p1 = 5 + 12*k and p2 = 5 + 14*k.

LINKS

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

EXAMPLE

11 is in the sequence since 11, ceil(11/2) + 11 = 17 and floor(17/2) + 11 = 19 are all primes.

MAPLE

N:= 100000: # to get all terms <= N

filter:= proc(p) local p1, p2;

if not isprime(p) then return false fi;

p1:= ceil(p/2)+p;

if not isprime(p1) then return false fi;

p2:= floor(p1/2)+p;

isprime(p2);

end;

select(filter, [2, seq(3+8*k, k=0 .. floor((N-3)/8))]);

CROSSREFS

Cf. A158714.

Sequence in context: A152024 A041441 A110482 * A105217 A066046 A065597

Adjacent sequences:  A242363 A242364 A242365 * A242367 A242368 A242369

KEYWORD

nonn

AUTHOR

Robert Israel and Vladimir Joseph Stephan Orlovsky, May 11 2014

STATUS

approved

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Last modified April 19 04:19 EDT 2019. Contains 322237 sequences. (Running on oeis4.)