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 A096784 Numbers n such that both n and n+1 are composite numbers that sum up to a prime. 11
 8, 9, 14, 15, 20, 21, 26, 33, 35, 39, 44, 48, 50, 51, 54, 56, 63, 65, 68, 69, 74, 75, 81, 86, 90, 95, 98, 99, 105, 111, 114, 116, 119, 120, 125, 128, 134, 135, 140, 141, 146, 153, 155, 158, 165, 168, 174, 176, 183, 186, 189, 194, 200, 204, 209, 215, 216, 219, 221 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS FORMULA Equals (A060254 -1)/2. MATHEMATICA Select[ Range[ 225], PrimeQ[ # ] == PrimeQ[ # + 1] == False && PrimeQ[2# + 1] == True &] (* Robert G. Wilson v, Jul 11 2004 *) PROG (PARI) nextcomposite(k)=if(k<3, 4, if(isprime(k), k+1, k)); {m=230; n=4; while(n

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Last modified October 23 22:23 EDT 2019. Contains 328373 sequences. (Running on oeis4.)