OFFSET
1,11
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Goldbach Partition
Wikipedia, Goldbach's conjecture
MAPLE
with(numtheory): A279794:=n->add( (pi(i)-pi(i-1)) * (pi(2*n-i)-pi(2*n-i-1)) * (1-signum(floor(n/(2*(n-i))))), i=3..n-1): seq(A279794(n), n=1..100);
# Alternative:
f:= proc(n) local p;
nops(select(t -> isprime(t) and isprime(2*n-t), [seq(p, p=3..(n-1)/2, 2)]))
end proc:
map(f, [$1..100]); # Robert Israel, Feb 15 2021
MATHEMATICA
Table[Sum[Boole[PrimeQ@ i] Boole[PrimeQ[2 n - i]] (1 - Sign@ Floor[n/(2 (n - i))]), {i, 3, n - 1}], {n, 100}] (* Michael De Vlieger, Dec 21 2016 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Dec 18 2016
STATUS
approved