OFFSET
1,1
COMMENTS
Odd composites numbers c such that 2*c + 1 is prime. - Alexandre Herrera, Jul 07 2023
FORMULA
Equals (A096787 - 1)/2.
MATHEMATICA
Select[ Range[ 450], PrimeQ[ # ] == PrimeQ[ # + 1] == False && PrimeQ[2# + 1, GaussianIntegers -> True] == True &] (* Robert G. Wilson v, Jul 11 2004 *)
PROG
(PARI) nextcomposite(k)=if(k<3, 4, if(isprime(k), k+1, k));
{m=455; n=4; while(n<m, k=nextcomposite(n+1); p=n+k; if(isprime(p)&&(p%4)==3, print1(n, ", ")); n=k)} \\ Klaus Brockhaus, Jul 10 2004
CROSSREFS
KEYWORD
nonn
AUTHOR
Lekraj Beedassy, Jul 09 2004
EXTENSIONS
Corrected and extended by Klaus Brockhaus and Ray Chandler, Jul 10 2000
Incorrect comment about Gaussian primes deleted by N. J. A. Sloane, Mar 02 2011
STATUS
approved