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A000570
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Number of tournaments on n nodes determined by their score vectors.
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4
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1, 1, 2, 4, 7, 11, 18, 31, 53, 89, 149, 251, 424, 715, 1204, 2028, 3418, 5761, 9708, 16358, 27565, 46452, 78279, 131910, 222285, 374581, 631222, 1063696, 1792472, 3020560, 5090059, 8577449, 14454177, 24357268, 41045336, 69167021, 116555915
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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REFERENCES
| Prasad Tetali, A characterization of unique tournaments, J. Comb Theory B 72 (1) (1998), 157-159.
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..500
Index entries for sequences related to tournaments
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FORMULA
| a(n) = a(n-5) + a(n-4) + a(n-3) + a(n-1). - Jon Schoenfield (jonscho(AT)hiwaay.net), Aug 07 2006
G.f.: (1+x^2+x^3+x^4)/(1-x-x^3-x^4-x^5) [From Harvey P. Dale, May 05 2011]
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MAPLE
| A000570 := proc(n) option remember; if n <= 2 then RETURN(1) elif n=3 then RETURN(2) elif n=4 then RETURN(4) elif n=5 then RETURN(7) else A000570(n-1)+A000570(n-3)+A000570(n-4)+A000570(n-5); fi; end;
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MATHEMATICA
| LinearRecurrence[{1, 0, 1, 1, 1}, {1, 1, 2, 4, 7}, 50] (* From Harvey P. Dale, May 05 2011 *)
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CROSSREFS
| Sequence in context: A091838 A004696 A018063 * A023426 A157134 A127926
Adjacent sequences: A000567 A000568 A000569 * A000571 A000572 A000573
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KEYWORD
| nonn,nice
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AUTHOR
| Prasad Tetali [ tetali(AT)math.gatech.edu ]
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EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu), Feb 06 2000
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