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A215251
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Product of terms in n-th row of A037306.
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2
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1, 1, 1, 2, 4, 36, 225, 7840, 313600, 45302400, 8930250000, 8373836401920, 9001015156742400, 41813367543204433176, 325385777102562972821025, 8270190445766978650521600000, 377177413291384771899817984000000, 62187743659065606074696974956949929984
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OFFSET
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1,4
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COMMENTS
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Also products of terms in rows of A047996.
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LINKS
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MAPLE
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with (numtheory):
a:= n-> mul (add(phi(d)*binomial(n/d, k/d),
d=divisors(igcd(n, k))), k=0..n)/n^(n+1):
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MATHEMATICA
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t[n_, k_] := Total[EulerPhi[#] * Binomial[n/#, k/#]& /@ Divisors[GCD[n, k]]]/n; Table[Times @@ Table[t[n, k], {k, 1, n}], {n, 1, 18}] (* Jean-François Alcover, Mar 07 2014 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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