OFFSET
1,1
COMMENTS
No term is the difference of two primes. - Juri-Stepan Gerasimov, Oct 10 2009
Goldbach's conjecture states that all even numbers > 2 can be expressed as the sum of two primes. If true, then this sequence contains all composites which cannot be expressed as the sum or difference of two primes. - Bob Selcoe, Mar 10 2015
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
Wikipedia, Goldbach's conjecture
EXAMPLE
93 is the first term because 91=7*13, 93=3*31 and 95=5*19 are all composite and there is no smaller odd composite with both odd neighbors composite.
MATHEMATICA
Select[Range@1200, OddQ@# && AllTrue[{# - 2, #, # + 2}, CompositeQ] &] (* Michael De Vlieger, Mar 10 2015, Version 10 *)
PROG
(PARI) forstep(n=9, 1000, 2, if(!isprime(n)&&!isprime(n-2)&&!isprime(n+2), print1(n, ", ")))
CROSSREFS
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Nov 13 2004
STATUS
approved