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A327804
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Leading coefficient of the n-th Stern polynomial.
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0
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0, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 3, 2, 3, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 3, 2, 2, 2, 3, 1, 1, 2, 1, 1, 1, 1, 1, 3, 2, 3, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 4, 3, 5, 2, 2, 2, 2, 2, 5, 3, 4, 1, 1, 1, 1, 2
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OFFSET
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0,6
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LINKS
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MATHEMATICA
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B[0, _] = 0; B[1, _] = 1; B[n_, t_] := B[n, t] = If[EvenQ[n], t B[n/2, t], B[1 + (n-1)/2, t] + B[(n-1)/2, t]];
a[n_] := Coefficient[B[n, t], t, Exponent[B[n, t], t]]; a[0] = 0;
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PROG
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(PARI) pol(n) = {if (n<2, return (n)); if (n%2, pol((n+1)/2) + pol((n-1)/2), x*pol(n/2)); }
a(n) = my(p=pol(n)); if (p==0, 0, polcoef(p, poldegree(p)));
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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