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 A171080 a(n) = Product_{3 <= q <= 2n+1, q prime} q^floor((2n/(q-1)). 4
 1, 3, 45, 945, 14175, 467775, 638512875, 1915538625, 488462349375, 194896477400625, 32157918771103125, 2218896395206115625, 3028793579456347828125, 9086380738369043484375, 3952575621190533915703125, 28304394023345413370350078125, 7217620475953080409439269921875 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES F. Hirzebruch, Topological Methods in Algebraic Geometry, Springer, 3rd. ed., 1966; Lemma 1.5.2, p. 13. LINKS MAPLE 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; MATHEMATICA 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 *) CROSSREFS Cf. A091137 Sequence in context: A036278 A225149 A154289 * A188681 A012827 A012769 Adjacent sequences:  A171077 A171078 A171079 * A171081 A171082 A171083 KEYWORD nonn AUTHOR N. J. A. Sloane, Sep 06 2010 STATUS approved

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Last modified November 28 04:43 EST 2021. Contains 349400 sequences. (Running on oeis4.)