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A000954

Conjecturally largest even integer which is an unordered sum of two primes in exactly n ways.

2, 12, 68, 128, 152, 188, 332, 398, 368, 488, 632, 692, 626, 992, 878, 908, 1112, 998, 1412, 1202, 1448, 1718, 1532, 1604, 1682, 2048, 2252, 2078, 2672, 2642, 2456, 2936, 2504, 2588, 2978, 3092, 3032, 3218, 3272, 3296, 3632, 3548, 3754, 4022, 4058, 4412

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OFFSET

0,1

COMMENTS

The Goldbach conjecture is that every even number is the sum of two primes.

LINKS

T. D. Noe, Table of n, a(n) for n = 0..5000

EXAMPLE

2 is largest even integer which is the sum of two primes in 0 ways, 12 is largest even integer which is the unordered sum of two primes in 1 way (5+7), etc.

MATHEMATICA

f[n_] := Block[{c = 0, k = 3}, While[k <= n/2, If[PrimeQ[k] && PrimeQ[n - k], c++ ]; k++ ]; c]; a = Table[0, {50}]; a[[1]] = 2; a[[2]] = 4; Do[m = n; b = f[n]; If[b < 100, a[[b + 1]] = n], {n, 6, 20000, 2}] (* Robert G. Wilson v, Dec 20 2003 *)

CROSSREFS

Cf. A045917, A023036, A000974, A001172, A002375.

Sequence in context: A185035 A185235 A226400 * A056636 A174327 A245997

Adjacent sequences: A000951 A000952 A000953 * A000955 A000956 A000957

KEYWORD

nonn,nice

AUTHOR

Bill Gosper

STATUS

approved