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 A100319 Even numbers m such that at least one of m-1 and m+1 is composite. 3
 8, 10, 14, 16, 20, 22, 24, 26, 28, 32, 34, 36, 38, 40, 44, 46, 48, 50, 52, 54, 56, 58, 62, 64, 66, 68, 70, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 104, 106, 110, 112, 114, 116, 118, 120, 122, 124, 126, 128, 130, 132, 134, 136, 140, 142, 144, 146, 148 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Subsequence of A100318. For each k >= 0, a(k+1) = a(k) + 2 unless a(k) + 1 and a(k) + 3 are twin primes, in which case a(k+1) = a(k) + 4 (as a(k) - 1 and a(k) + 5 are divisible by 3). The even nonisolated primes(n+1). - Juri-Stepan Gerasimov, Nov 09 2009 LINKS G. C. Greubel, Table of n, a(n) for n = 1..1000 FORMULA a(n) = A167692(n+1). - Juri-Stepan Gerasimov, Nov 09 2009 MATHEMATICA Select[2*Range, CompositeQ[#-1] || CompositeQ[#+1] &]  (* G. C. Greubel, Mar 09 2019 *) PROG (PARI) forstep(n=4, 300, 2, if(isprime(n-1)+isprime(n+1)<=1, print1(n, ", "))) (Sage) [n for n in (3..250) if mod(n, 2)==0 and (is_prime(n-1) + is_prime(n+1)) < 2] # G. C. Greubel, Mar 09 2019 CROSSREFS Cf. A100318 (supersequence containing odd and even n), A045718 (n such that at least one of n-1 and n+1 is prime). Cf. A167692(the even nonisolated nonprimes). - Juri-Stepan Gerasimov, Nov 09 2009 Cf. A005818, A038179, A007310, A038511, A025584. Complement of A014574 (average of twin prime pairs) w.r.t. A005843 (even numbers), except for missing term 2. Sequence in context: A308874 A030490 A076639 * A167692 A171689 A163628 Adjacent sequences:  A100316 A100317 A100318 * A100320 A100321 A100322 KEYWORD nonn AUTHOR Rick L. Shepherd, Nov 13 2004 STATUS approved

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Last modified July 13 08:26 EDT 2020. Contains 335685 sequences. (Running on oeis4.)