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Search: id:A120972
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| A120972 |
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G.f. satisfies: A(x/A(x)^3) = 1 + x ; thus A(x) = 1 + series_reversion(x/A(x)^3). |
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+0
6
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| 1, 1, 3, 21, 217, 2814, 42510, 718647, 13270944, 263532276, 5567092665, 124143735663, 2905528740060, 71058906460091, 1809695198254281, 47861102278428198, 1311488806252697283, 37164457324943708739
(list; graph; listen)
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OFFSET
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0,3
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FORMULA
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G.f. satisfies: A(x) = 1 + x*B(x)^3 = 1 + (1 + x*C(x)^3 )^3 where B(x) and C(x) satisfy: C(x) = B(x)*B(A(x)-1), B(x) = A(A(x)-1), B(A(x)-1) = A(B(x)-1), B(x/A(x)^3) = A(x), B(x) = A(x*B(x)^3) and B(x) is g.f. of A120973.
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PROGRAM
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(PARI) {a(n)=local(A=[1, 1]); for(i=2, n, A=concat(A, 0); A[ #A]=-Vec(subst(Ser(A), x, x/Ser(A)^3))[ #A]); A[n+1]}
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CROSSREFS
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Cf. A120973; variants: A120970, A120974, A120976, A030266, A067145, A107096.
Sequence in context: A123691 A087918 A088926 this_sequence A158838 A107716 A032033
Adjacent sequences: A120969 A120970 A120971 this_sequence A120973 A120974 A120975
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Jul 20 2006
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