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A087747
Least number expressible as a sum of two distinct primes in exactly n ways.
4
5, 16, 24, 36, 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, 1080, 1230, 1518
OFFSET
1,1
LINKS
FORMULA
a(n) = min({m >= 1 : A117929(m) = n}). - Peter Munn, May 01 2023
EXAMPLE
a(2)=16 because we have 16=3+13=5+11, followed by 18=5+13=7+11; 20=3+17=7+13; 22=3+19=5+17; 26=3+23=7+19;...
MATHEMATICA
Module[{nn=2000, ip}, ip=Table[{n, Length[Select[IntegerPartitions[n, {2}], #[[1]]!=#[[2]]&&AllTrue[#, PrimeQ]&]]}, {n, nn}]; Table[SelectFirst[ip, #[[2]]==k&], {k, 60}]][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 11 2020 *)
CROSSREFS
Cf. A117929.
Sequence in context: A278415 A063243 A063232 * A352754 A090785 A069482
KEYWORD
nonn
AUTHOR
Lekraj Beedassy, Oct 02 2003
EXTENSIONS
More terms from John Dethridge (jcd(AT)ms.unimelb.edu.au), Jan 08 2004
More terms from Hugo Pfoertner, Sep 23 2004
Reinserted a(18), a(19) and a(20) by Paolo P. Lava, May 26 2014
STATUS
approved