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%I #20 Oct 13 2018 09:13:57
%S 1,1,2,2,3,3,3,3,3,3,5,4,5,3,4,3,3,7,4,5,4,3,5,5,6,5,5,4,4,3,7,5,5,7,
%T 5,5,6,4,6,5,5,7,4,6,5,4,6,5,8,5,7,4,5,6,5,3,3,8,8,5,4,5,8,8,5,5,9,4,
%U 8,7,7,6,6,5,5,7,5,7,7,6,6,6,6,5,7,7,6,6,5,6,5,5,7,4,8,4,8,5,8,7,8,9,7,5,9
%N Form an addition table of the primes; a(n) is the number of even numbers that appear for the first time in column n.
%C 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
%H Reinhard Zumkeller, <a href="/A105047/b105047.txt">Table of n, a(n) for n = 1..1000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GoldbachPartition.html">Goldbach Partition</a>
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Goldbach%27s_conjecture">Goldbach's conjecture</a>
%H <a href="/index/Go#Goldbach">Index entries for sequences related to Goldbach conjecture</a>
%e The addition table is as follows:
%e + | 2 3 5 7 11
%e --+--------------
%e 2 | 4 5 7 9 13
%e 3 | 6 8 10 14
%e 5 | 10 12 16
%e 7 | 14 18
%e 11 | 22
%o (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
%o (Haskell)
%o a105047 1 = 1
%o a105047 n = length $ a260580_row (n - 1)
%o -- _Reinhard Zumkeller_, Aug 11 2015
%Y Cf. A102696, A260580.
%K nonn
%O 1,3
%A _Andrew S. Plewe_, Apr 06 2005
%E More terms from _Reinhard Zumkeller_, Apr 19 2005
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