OFFSET
1,3
COMMENTS
For n > 2: a(n) = A102696(n-1) - A102696(n-2); a(n+1) = length of n-th row in the triangle A260580. - Reinhard Zumkeller, Aug 11 2015
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Goldbach Partition
Wikipedia, Goldbach's conjecture
EXAMPLE
The addition table is as follows:
+ | 2 3 5 7 11
--+--------------
2 | 4 5 7 9 13
3 | 6 8 10 14
5 | 10 12 16
7 | 14 18
11 | 22
PROG
(PARI) lista(n) = {maxp = prime(n); v = vector(maxp); forprime (p=1, maxp, nb = 0; forprime (q=1, p, s = p+q; if (! (s % 2), if (!v[s/2], nb++); v[s/2] = 1; ); ); print1(nb, ", "); ); } \\ Michel Marcus, Apr 18 2013
(Haskell)
a105047 1 = 1
a105047 n = length $ a260580_row (n - 1)
-- Reinhard Zumkeller, Aug 11 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew S. Plewe, Apr 06 2005
EXTENSIONS
More terms from Reinhard Zumkeller, Apr 19 2005
STATUS
approved