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%I #6 Jan 21 2019 23:17:08
%S 59,60,61,72,93,102,103,108,109,123,144,149,150,151,161,162,163,171,
%T 207,213,236,237,257,258,264,265,266,267,268,276,291,312,313,318,333,
%U 334,348,357,389,390,391,396,401,402,408,417,422,423,424,434,435,436,446
%N Numbers k such that 2k-3, 2k-1, 2k+1 and 2k+3 are composite.
%C Almost all numbers are in this sequence, by the Prime Number Theorem.
%e a(1)=59 because 2*59-1=117, 2*59+1=119, 2*59-3=115 and 2*59+3=121 are all composite.
%p a := proc (n): if isprime(2*n-3) = false and isprime(2*n-1) = false and isprime(2*n+1) = false and isprime(2*n+3) = false then n else end if end proc: seq(a(n), n = 1 .. 500); # _Emeric Deutsch_, Feb 15 2010
%Y Cf. A104278.
%K nonn,easy,less
%O 1,1
%A _Juri-Stepan Gerasimov_, Feb 03 2010
%E Corrected and extended by _Emeric Deutsch_, Feb 15 2010
%E Comment from _Charles R Greathouse IV_, Mar 25 2010