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1, 9, 4, 36, 16, 9, 81, 4, 64, 35, 36, 49, 16, 25, 144, 15, 9, 16, 100, 81, 49, 4, 64, 35, 36, 196, 16, 15, 25, 49, 25, 144, 9, 60, 9, 100, 64, 100, 121, 15, 16, 81, 16, 4, 81, 9, 25, 16, 49, 4, 25, 16, 121, 25, 35, 256, 114, 36, 35, 81, 4, 49, 16, 16, 36, 4, 64
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OFFSET
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1,2
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COMMENTS
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Almost all terms are squares.
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LINKS
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Amiram Eldar, Table of n, a(n) for n = 1..1000
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FORMULA
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a(n) = f(A122839(n)), where f(m) = A000203(m)*A034448(m)/A047994(m)^2. - Amiram Eldar, Dec 11 2019
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MATHEMATICA
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f[p_, e_] := (p^(e+1)-1)*(p^e+1)/(p-1)/(p^e-1)^2; ratio[1] = 1; ratio[n_] := Times @@ (f @@@ FactorInteger[n]); Select[ratio /@ Range[10^5], IntegerQ] (* Amiram Eldar, Dec 11 2019 *)
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CROSSREFS
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Cf. A000203, A034448, A047994, A122839.
Sequence in context: A104728 A058093 A164032 * A248309 A317900 A298583
Adjacent sequences: A122843 A122844 A122845 * A122847 A122848 A122849
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KEYWORD
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nonn
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AUTHOR
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Yasutoshi Kohmoto, Oct 23 2006
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EXTENSIONS
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More terms from Amiram Eldar, Dec 11 2019
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STATUS
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approved
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