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A001172 Smallest even number that is an unordered sum of two odd primes in exactly n ways.
(Formerly M4085 N1694)
15

%I M4085 N1694

%S 0,6,10,22,34,48,60,78,84,90,114,144,120,168,180,234,246,288,240,210,

%T 324,300,360,474,330,528,576,390,462,480,420,570,510,672,792,756,876,

%U 714,798,690,1038,630,1008,930,780,960,870,924,900,1134,1434,840,990,1302

%N Smallest even number that is an unordered sum of two odd primes in exactly n ways.

%C a(n) = A023036(n) for all n > 1.

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H T. D. Noe, <a href="/A001172/b001172.txt">Table of n, a(n) for n = 0..10000</a>

%H Eric Wolman, <a href="/A001172/a001172.pdf">Letter to N. J. A. Sloane</a>, 1970.

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

%t nn = 55; a = Table[0, {nn}]; n = 6; While[Times @@ a == 0, c = 0; k = 3; While[k <= n/2, If[PrimeQ[k] && PrimeQ[n - k], c++]; k++]; If[c <= nn && a[[c]] == 0, a[[c]] = n]; n = n + 2]; Prepend[a, 0]

%Y Cf. A000954, A000974, A002375, A005843, A023036.

%Y Divided by 2: A258713.

%K nonn,nice,look,easy

%O 0,2

%A _N. J. A. Sloane_, Eric Wolman, Dec 17 1969

%E a(0) corrected by _Zak Seidov_, Sep 30 2011

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Last modified August 21 23:28 EDT 2019. Contains 326169 sequences. (Running on oeis4.)