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A162918
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Natural numbers n such that there are s and w satisfying 0 < s < w and 2*s + 5*w = n.
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0
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12, 17, 19, 22, 24, 26, 27, 29, 31, 32, 33, 34, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92
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OFFSET
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1,1
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COMMENTS
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Number of equal microtone intervals dividing a musical octave, so that it is (formally) possible to compose one octave (according to the diatonic scale) of two semi-tone-steps and five whole-tone-steps, each being a multiple of the microtone interval.
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LINKS
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EXAMPLE
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12 = 2*1 + 5*2
17 = 2*1 + 5*3
19 = 2*2 + 5*3
22 = 2*1 + 5*4
...
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MATHEMATICA
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Union[2*First[#]+5*Last[#]&/@Subsets[Range[20], {2}]] (* Harvey P. Dale, Mar 28 2012 *)
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PROG
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(Haskell)
filter (\n -> [ (s, w) | s<-[1..n], w<-[(s+1)..n], 2*s+5*w == n ] /= []) [1..]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Jan Behrens (jbe-oeis(AT)magnetkern.de), Jul 17 2009
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STATUS
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approved
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