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Andrew Howroyd, <a href="/A304482/b304482_1.txt">Table of n, a(n) for n = 0..1325</a> (first 51 antidiagonals)
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Andrew Howroyd, <a href="/A304482/b304482_1.txt">Table of n, a(n) for n = 0..1325</a> (first 51 antidiagonals)
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Andrew Howroyd, <a href="/A304482/b304482_1.txt">Table of n, a(n) for n = 0..1325</a> (first 51 antidiagonals)
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editing
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proposed
A[n_, k_] : = (-1)^n (1/n) Sum[Binomial[k d, d] (-1)^d EulerPhi[n/d], {d, Divisors[n]}]; A[0, 0] = 1; A[_, 0] = 0; A[0, _] = 1;
Table[A[n-k, k], {n, 0, 11}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Sep 23 2019 *)
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