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A143918
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G.f. A(x) satisfies: A(x) = 1/(1-x)^2 + x^2*A'(x).
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0
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1, 2, 5, 14, 47, 194, 977, 5870, 41099, 328802, 2959229, 29592302, 325515335, 3906184034, 50780392457, 710925494414, 10663882416227, 170622118659650, 2900576017214069, 52210368309853262, 991996997887211999
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OFFSET
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0,2
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LINKS
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Table of n, a(n) for n=0..20.
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FORMULA
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a(n) = 3*floor(e*(n-1)!)-1, n>1 [From Gary Detlefs, Jun 10 2010]
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EXAMPLE
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G.f.: A(x) = 1 + 2*x + 5*x^2 + 14*x^3 + 47*x^4 + 194*x^5 + 977*x^6 +...
x^2*A'(x) = 2*x^2 + 10*x^3 + 42*x^4 + 188*x^5 + 970*x^6 + 5862*x^7 +...
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MATHEMATICA
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a=2; lst={}; Do[a=n+a*(n-2); AppendTo[lst, a], {n, 0, 3*4!}]; lst [From Vladimir Joseph Stephan Orlovsky, Mar 16 2010]
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PROG
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(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=1, n, A=1/(1-x+x*O(x^n))^2+x^2*deriv(A)); polcoeff(A, n)}
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CROSSREFS
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Sequence in context: A096402 A007268 A109156 * A129867 A119841 A149905
Adjacent sequences: A143915 A143916 A143917 * A143919 A143920 A143921
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna, Sep 05 2008
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STATUS
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approved
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