OFFSET
1,2
COMMENTS
Complement of A216075.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
EXAMPLE
7 is in the sequence because 2*17-19=15 and 15 is not prime.
MATHEMATICA
f[n_]: = (2 Prime[n] - Prime[n + 1]); Select[Range[110], ! PrimeQ[f[#]]&]
Flatten[Position[2#[[1]]-#[[2]]&/@Partition[Prime[Range[100]], 2, 1], _?(!PrimeQ[#]&)]] (* Harvey P. Dale, Jan 12 2016 *)
PROG
(Magma) [n: n in [1..100]| not IsPrime(2*NthPrime(n) - NthPrime(n+1))];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Aug 21 2013
STATUS
approved