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 A096786 Numbers n such that both n and n+1 are composite numbers that sum up to a Pythagorean prime (i.e., of the form 4k+1). 10
 8, 14, 20, 26, 44, 48, 50, 54, 56, 68, 74, 86, 90, 98, 114, 116, 120, 128, 134, 140, 146, 158, 168, 174, 176, 186, 194, 200, 204, 216, 224, 230, 254, 260, 278, 284, 288, 296, 300, 308, 320, 326, 338, 350, 354, 380, 384, 386, 398, 404, 410, 414, 426, 428, 440 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..55. FORMULA Equals (A096785 - 1)/2. MATHEMATICA Select[ Range[450], PrimeQ[ # ] == PrimeQ[ # + 1] == PrimeQ[2# + 1, GaussianIntegers -> True] == 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=465; n=4; while(n

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Last modified August 6 00:15 EDT 2024. Contains 374957 sequences. (Running on oeis4.)