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A176897 Primes p such that (p+1)/2 is not prime. 1

%I

%S 2,7,11,17,19,23,29,31,41,43,47,53,59,67,71,79,83,89,97,101,103,107,

%T 109,113,127,131,137,139,149,151,163,167,173,179,181,191,197,199,211,

%U 223,227,229,233,239,241,251,257,263,269,271,281,283,293,307,311,317,331

%N Primes p such that (p+1)/2 is not prime.

%C Primes not in A005383. 2 together with A034849.

%C The Ramanujan primes, A104272, are a subsequence.

%t Select[Prime[Range[100]], ! PrimeQ[(#+1)/2] &]

%K nonn

%O 1,1

%A _Juri-Stepan Gerasimov_, Apr 28 2010

%E Entries checked by _R. J. Mathar_, May 01 2010

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Last modified April 19 11:58 EDT 2021. Contains 343114 sequences. (Running on oeis4.)