OFFSET
1,1
COMMENTS
A subsequence of A005382, primes p such that 2p-1 is also prime. Note that for all n, 2a(n)-1 is not in this sequence.
LINKS
T. D. Noe, Table of n, a(n) for n=1..1000
Jeffery J. Holt, The minimal number of solutions to phi(n)=phi(n+k), Math. Comp., 72 (2003), 2059-2061.
MATHEMATICA
Select[Prime[Range[2, 1000]], PrimeQ[2#-1] && !PrimeQ[4#-3]&]
PROG
(Magma) [p: p in PrimesUpTo(2600) | IsPrime(2*p-1) and not IsPrime(4*p-3)]; // Vincenzo Librandi, Apr 14 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
T. D. Noe, Jul 28 2005
STATUS
approved