OFFSET
1,9
LINKS
Lei Zhou, Table of n, a(n) for n = 1..10000
EXAMPLE
a(5)=1 because 2*5 = 5 + 5.
MAPLE
A171611 := proc(n) a := 0 ; for i from 3 do p := ithprime(i) ; q := 2*n-p ; if q < p then return a ; end if; if isprime(q) then a := a+1 ; end if; if q <= p then return a ; end if; end do: end proc:
seq(A171611(n), n=1..120) ; # R. J. Mathar, May 22 2010
MATHEMATICA
Table[s = 2*n; ct = 0; p = 3; While[p = NextPrime[p]; p <= n, If[PrimeQ[s - p], ct++]]; ct, {n, 100}] (* Lei Zhou, Apr 10 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Dec 13 2009
EXTENSIONS
a(38) changed from 5 to 4 and a(79) and a(82) changed by R. J. Mathar, May 22 2010
STATUS
approved