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A171080
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a(n) = Product_{3 <= q <= 2n+1, q prime} q^floor((2n/(q-1)).
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5
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1, 3, 45, 945, 14175, 467775, 638512875, 1915538625, 488462349375, 194896477400625, 32157918771103125, 2218896395206115625, 3028793579456347828125, 9086380738369043484375, 3952575621190533915703125, 28304394023345413370350078125, 7217620475953080409439269921875
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OFFSET
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0,2
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REFERENCES
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F. Hirzebruch, Topological Methods in Algebraic Geometry, Springer, 3rd. ed., 1966; Lemma 1.5.2, p. 13.
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LINKS
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Table of n, a(n) for n=0..16.
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MAPLE
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f:=proc(n) local q, t1; t1:=1; for q from 3 to 2*n+1 do if isprime(q) then t1:=t1*q^floor(2*n/(q-1)); fi; od; t1; end;
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MATHEMATICA
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a[n_] := Product[If[PrimeQ[q], q^Floor[2 n/(q - 1)], 1], {q, 3, 2 n + 1}]
Table[a[n], {n, 0, 20}] (* Wolfgang Hintze, Oct 03 2014 *)
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CROSSREFS
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Cf. A091137
Sequence in context: A036278 A225149 A154289 * A188681 A012827 A012769
Adjacent sequences: A171077 A171078 A171079 * A171081 A171082 A171083
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, Sep 06 2010
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STATUS
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approved
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