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Search: id:A059517
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| A059517 |
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The sequence A059515(3,n). Number of ways of placing n identifiable nonnegative intervals with a total of exactly three starting and/or finishing points. |
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+0
1
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| 0, 0, 12, 138, 1056, 7050, 44472, 273378, 1659936, 10018650, 60289032, 362265618, 2175188016, 13055911050, 78349815192, 470141937858, 2820980767296, 16926272024250, 101558794406952, 609356253226098
(list; graph; listen)
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OFFSET
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0,3
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LINKS
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IBM Ponder This, Jan. 2001
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FORMULA
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a(n) =A058809(n)+A059116(n) =6^n-3*3^n+3 (for n>0).
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EXAMPLE
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a(2)=12 since if aA indicates a zero length interval and a-A one of positive length the possibilities are: aA-b-B, b-aA-B, b-B-aA, bB-a-A, a-bB-A, a-A-bB, ab-A-B, ab-B-A, a-b-AB, b-a-AB, a-bA-B, b-a-AB.
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CROSSREFS
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Cf. A059516.
Sequence in context: A085938 A030023 A000467 this_sequence A097167 A125469 A113366
Adjacent sequences: A059514 A059515 A059516 this_sequence A059518 A059519 A059520
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KEYWORD
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nonn
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AUTHOR
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Henry Bottomley (se16(AT)btinternet.com), Jan 19 2001
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