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A107088
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G.f. A(x) satisfies: A(x) = A(x^2)^(1/2) + 4*x.
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4
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1, 4, 2, 0, -1, 0, 2, 0, -5, 0, 12, 0, -30, 0, 82, 0, -233, 0, 668, 0, -1949, 0, 5802, 0, -17503, 0, 53302, 0, -163783, 0, 507418, 0, -1582869, 0, 4966790, 0, -15667573, 0, 49658264, 0, -158059506, 0, 505013014, 0, -1619144976, 0, 5207596574, 0, -16797286048, 0, 54323516786, 0, -176113786590, 0
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OFFSET
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0,2
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COMMENTS
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LINKS
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EXAMPLE
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A(x) = 1 + 4*x + 2*x^2 - x^4 + 2*x^6 - 5*x^8 + 12*x^10 - 30*x^12 +...
A(x^2)^(1/2) = 1 + 2*x^2 - x^4 + 2*x^6 - 5*x^8 + 12*x^10 - 30*x^12 +...
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PROG
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(PARI) {a(n)=local(A=1+x); for(i=1, n, A=subst(A, x, x^2)^(1/2)+4*x+x*O(x^n)); polcoeff(A, n, x)}
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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