OFFSET
1,6
COMMENTS
Conjecture: a(n) > 0 for all n > 3.
LINKS
Zhi-Wei Sun, Table of n, a(n) for n = 1..10000
EXAMPLE
a(4) = 1 since 4 = 2 + 2 with 2*(2+1) - prime(2) = 3 prime.
a(5) = 1 since 5 = 2 + 3 with 2*(2+1) - prime(2) = 3 and 3*(3+1) - prime(3) = 7 both prime.
MATHEMATICA
p[n_]:=PrimeQ[n(n+1)-Prime[n]]
a[n_]:=Sum[If[p[k]&&p[n-k], 1, 0], {k, 1, n/2}]
Table[a[n], {n, 1, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Zhi-Wei Sun, Jan 12 2014
STATUS
approved