A046926 - OEIS

%I #16 Jul 23 2021 09:03:00

%S 0,0,0,0,0,1,1,1,2,0,2,1,2,0,2,1,4,0,2,0,3,0,3,1,3,0,4,1,4,0,2,0,5,0,

%T 3,1,4,0,4,1,5,0,4,0,6,0,4,1,4,0,7,0,5,0,3,0,7,0,3,1,3,0,7,1,7,0,5,0,

%U 7,0,4,0,4,0,8,1,7,0,5,0,8,0,4,1,7,0,8,1,7,0,4,0,11,0,5,1,6,0,9

%N Number of ways to express n as p+2q; p, q primes.

%H Charles R Greathouse IV, <a href="/A046926/b046926.txt">Table of n, a(n) for n = 1..10000</a>

%H L. Hodges, <a href="https://www.jstor.org/stable/2690477">A lesser-known Goldbach conjecture</a>, Math. Mag., 66 (1993), 45-47.

%H <a href="/index/Go#Goldbach">Index entries for sequences related to Goldbach conjecture</a>

%o (PARI) a(n)=my(s);forprime(p=2,n\2-1,if(isprime(n-2*p),s++));s \\ _Charles R Greathouse IV_, Jul 22 2015

%K nonn

%O 1,9

%A _David W. Wilson_