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A025555
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Least common multiple (or LCM) of first n triangular numbers (A000217).
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4
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1, 3, 6, 30, 30, 210, 420, 1260, 1260, 13860, 13860, 180180, 180180, 180180, 360360, 6126120, 6126120, 116396280, 116396280, 116396280, 116396280, 2677114440, 2677114440, 13385572200, 13385572200, 40156716600, 40156716600
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..200
Peter Luschny and Stefan Wehmeier, The lcm(1,2,...,n) as a product of sine values sampled over the points in Farey sequences
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EXAMPLE
| a(5) = LCM{1, 3, 6, 10, 15} = 30.
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MAPLE
| HalfFarey := proc (n) local a, b, c, d, k, s; if n<2 then RETURN([1]) fi; a:=0; b:=1; c:=1; d:=n; s:=NULL; do k := iquo(n+b, d); a, b, c, d := c, d, k*c-a, k*d-b; if b < 2*a then break fi; s := s, a/b od; [s] end:
A025555 := proc(n) local r; HalfFarey(n+1); subsop(nops(%) = NULL, %); mul(2*sin(Pi*r), r = %)^2 end: seq(round(evalf(A025555(i))), i=1..27); # Peter Luschny, Jun 9 2011
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MATHEMATICA
| nn=30; With[{trnos=Accumulate[Range[nn]]}, Table[LCM@@Take[trnos, n], {n, nn}]] (* From Harvey P. Dale, Oct 21 2011 *)
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CROSSREFS
| Sequence in context: A007452 A046981 A065943 * A200925 A140814 A136932
Adjacent sequences: A025552 A025553 A025554 * A025556 A025557 A025558
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KEYWORD
| easy,nice,nonn
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AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu) and Asher Auel (asher.auel(AT)reed.edu)
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EXTENSIONS
| Corrected by James A. Sellers (sellersj(AT)math.psu.edu)
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