A046926 Number of ways to express n as p+2q; p, q primes.

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, 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, 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

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
• L. Hodges, A lesser-known Goldbach conjecture, Math. Mag., 66 (1993), 45-47.
• Index entries for sequences related to Goldbach conjecture

Programs

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