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Search: id:A006605
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| A006605 |
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Number of modes of connections of 2n points.
(Formerly M2899)
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+0
3
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| 1, 1, 3, 11, 46, 207, 979, 4797, 24138, 123998, 647615, 3428493, 18356714, 99229015, 540807165, 2968468275, 16395456762, 91053897066, 508151297602, 2848290555562, 16028132445156, 90516256568235, 512831902620465
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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H. N. V. Temperley and D. G. Rogers, A note on Baxter's generalization of the Temperley-Lieb operators, pp. 324-328 of Combinatorial Mathematics (Canberra, 1977), Lect. Notes Math. 686, 1978.
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FORMULA
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Reference gives explicit formula.
G.f.: A(x) = (1/x)*serreverse(x/G(x)) where G(x) is g.f. of A001006 (Motzkin numbers). G.f. satisfies: A(x)^2 = (1/x)*serreverse( x/(1+x+x^2)^2 ). - Paul D. Hanna (pauldhanna(AT)juno.com), Mar 20 2005
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PROGRAM
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(PARI) {a(n)=polcoeff(((1/x)*serreverse(x/(1+x+x^2)^2+x^2*O(x^n)))^(1/2), n)} (Hanna)
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CROSSREFS
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Cf. A001006.
Adjacent sequences: A006602 A006603 A006604 this_sequence A006606 A006607 A006608
Sequence in context: A030889 A030854 A027135 this_sequence A086521 A046996 A129579
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KEYWORD
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nonn
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AUTHOR
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njas
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EXTENSIONS
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More terms from Pab Ter (pabrlos2(AT)yahoo.com), Nov 20 2005
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