OFFSET
1,1
COMMENTS
22397 and 22409 are first consecutive primes in this sequence. - Altug Alkan, Dec 22 2015
The next consecutive primes in this sequence are 134093 and 134129, 405541 and 405553, 432073 and 432097, 480803 and 480827, 586213 and 586237, ... - Harvey P. Dale, Dec 25 2015
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
lastp:= 3:
count:= 0:
while count < 100 do
p:= nextprime(lastp);
if isprime((lastp*p+1)/2) then
count:= count+1;
A[count]:= lastp;
fi;
lastp:= p;
od:
seq(A[i], i=1..100);
MATHEMATICA
Prime@ Select[Range@ 2620, PrimeQ[(Prime@ # Prime[# + 1] + 1)/2] &] (* Michael De Vlieger, Dec 22 2015 *)
Transpose[Select[Partition[Prime[Range[50000]], 2, 1], PrimeQ[ (Times@@#+1)/2]&]] [[1]] (* Harvey P. Dale, Dec 25 2015 *)
PROG
(PARI) lista(nn) = {forprime(p=3, nn, if(ispseudoprime((p*nextprime(p+1)+1)/2), print1(p, ", "))); } \\ Altug Alkan, Dec 22 2015
(Magma) [p: p in PrimesInInterval(3, 3*10^4) | IsPrime((p*NextPrime(p+1)+1) div 2)]; // Vincenzo Librandi, Dec 23 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Dec 22 2015
STATUS
approved