A001172 - OEIS

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A001172

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

0, 6, 10, 22, 34, 48, 60, 78, 84, 90, 114, 144, 120, 168, 180, 234, 246, 288, 240, 210, 324, 300, 360, 474, 330, 528, 576, 390, 462, 480, 420, 570, 510, 672, 792, 756, 876, 714, 798, 690, 1038, 630, 1008, 930, 780, 960, 870, 924, 900, 1134, 1434, 840, 990, 1302

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

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

REFERENCES

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

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

LINKS

T. D. Noe, Table of n, a(n) for n = 0..10000

Eric Wolman, Letter to N. J. A. Sloane, 1970.

Index entries for sequences related to Goldbach conjecture

MATHEMATICA

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]

CROSSREFS

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

Divided by 2: A258713.

Sequence in context: A189992 A255746 A082917 * A339437 A108605 A216049

Adjacent sequences: A001169 A001170 A001171 * A001173 A001174 A001175

KEYWORD

nonn,nice,look,easy

AUTHOR

N. J. A. Sloane, Eric Wolman, Dec 17 1969

EXTENSIONS

a(0) corrected by Zak Seidov, Sep 30 2011

STATUS

approved