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A083954
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Least integer coefficients of A(x), where 1<=a(n)<=4, such that A(x)^(1/4) consists entirely of integer coefficients.
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19
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1, 4, 2, 4, 3, 4, 4, 4, 1, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 2, 4, 2, 4, 4, 4, 4, 4, 3, 4, 2, 4, 2, 4, 2, 4, 3, 4, 2, 4, 3, 4, 2, 4, 4, 4, 2, 4, 2, 4, 4, 4, 2, 4, 4, 4, 2, 4, 2, 4, 1, 4, 4, 4, 1, 4, 2, 4, 4, 4, 4, 4, 1, 4, 2, 4, 3, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 2, 4, 2, 4, 2, 4, 2, 4, 1, 4, 4, 4, 1, 4, 2, 4, 3
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OFFSET
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0,2
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COMMENTS
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More generally, "least integer coefficients of A(x), where 1<=a(n)<=m, such that A(x)^(1/m) consists entirely of integer coefficients", appears to have a unique solution for all m>0. Is this sequence periodic?
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LINKS
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MATHEMATICA
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a[0] = 1; a[n_] :=a[n] = Block[{k=1, s = Sum[a[i]*x^i, {i, 0, n-1}]}, While[ Union[ IntegerQ /@ CoefficientList[ Series[(s+k*x^n)^(1/4), {x, 0, n}], x]] != {True}, k++ ]; k]; Table[ a[n], {n, 0, 104}] (* Robert G. Wilson v *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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