The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A025555 Least common multiple (or LCM) of first n positive triangular numbers (A000217). 6
 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; text; internal format)
 OFFSET 1,2 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 FORMULA a(n) = A003418(n+1)/2. - Matthew Vandermast, Jun 04 2012 EXAMPLE a(5) = lcm{1, 3, 6, 10, 15} = 30. 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 09 2011 MATHEMATICA nn=30; With[{trnos=Accumulate[Range[nn]]}, Table[LCM@@Take[trnos, n], {n, nn}]] (* Harvey P. Dale, Oct 21 2011 *) f[x_] := x + 1; a[1] = f[1]; a[n_] := LCM[f[n], a[n - 1]]; Array[a, 30]/2 (* Robert G. Wilson v, Jan 04 2013 *) PROG (Haskell) a025555 n = a025555_list !! (n-1) a025555_list = scanl1 lcm \$ tail a000217_list -- Reinhard Zumkeller, Nov 22 2013 (PARI) S=1; for(n=1, 20, S=lcm(S, n*(n+1)/2); print1(S, ", ")) \\ Edward Jiang, Sep 08 2014 CROSSREFS Cf. A051543, A051538. Sequence in context: A046981 A065943 A275786 * A200925 A140814 A343433 Adjacent sequences:  A025552 A025553 A025554 * A025556 A025557 A025558 KEYWORD easy,nice,nonn AUTHOR Clark Kimberling and Asher Auel (asher.auel(AT)reed.edu) EXTENSIONS Corrected by James A. Sellers Definition rendered more precisely by Reinhard Zumkeller, Nov 22 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 18 15:58 EDT 2021. Contains 347527 sequences. (Running on oeis4.)