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 A025547 Least common multiple of {1,3,5,...,2n-1}. 34
 1, 3, 15, 105, 315, 3465, 45045, 45045, 765765, 14549535, 14549535, 334639305, 1673196525, 5019589575, 145568097675, 4512611027925, 4512611027925, 4512611027925, 166966608033225, 166966608033225, 6845630929362225, 294362129962575675, 294362129962575675 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS This sequence coincides with the sequence f(n) = denominator of 1 + 1/3 + 1/5 + 1/7 + ... + 1/(2n-1) iff n <= 38. But a(39) = 6414924694381721303722858446525, f(39) = 583174972216520118520259858775. - T. D. Noe, Aug 04 2004 [See A350670(n-1).] Coincides for n=1..42 with the denominators of a series for Pi*sqrt(2)/4 and then starts to differ. See A127676. a(floor((n+1)/2)) = gcd(a(n), A051426(n)). - Reinhard Zumkeller, Apr 25 2011 A051417(n) = a(n+1)/a(n). LINKS T. D. Noe, Table of n, a(n) for n = 1..200 Eric Weisstein's World of Mathematics, Jeep Problem, Pi, Pi Continued Fraction, Least Common Multiple Wikipedia, Least common multiple Index entries for sequences related to lcm's MAPLE A025547:=proc(n) local i, t1; t1:=1; for i from 1 to n do t1:=lcm(t1, 2*i-1); od: t1; end; f := n->denom(add(1/(2*k-1), k=0..n)); # a different sequence! MATHEMATICA a = 1; Join[{1}, Table[a = LCM[a, n], {n, 3, 125, 2}]] (* Zak Seidov, Jan 18 2011 *) nn=30; With[{c=Range[1, 2*nn, 2]}, Table[LCM@@Take[c, n], {n, nn}]] (* Harvey P. Dale, Jan 27 2013 *) PROG (Haskell) a025547 n = a025547_list !! (n-1) a025547_list = scanl1 lcm a005408_list -- Reinhard Zumkeller, Oct 25 2013, Apr 25 2011 (PARI) a(n)=lcm(vector(n, k, 2*k-1)) \\ Charles R Greathouse IV, Nov 20 2012 (Python) # generates initial segment of sequence from math import gcd from itertools import accumulate def lcm(a, b): return a * b // gcd(a, b) def aupton(nn): return list(accumulate((2*i+1 for i in range(nn)), lcm)) print(aupton(23)) # Michael S. Branicky, Mar 28 2022 CROSSREFS Cf. A007509, A025550, A075135. The numerators are in A074599. Cf. A003418 (LCM of {1..n}). Cf. A005408, A350670. Sequence in context: A293996 A229726 A145624 * A352395 A350670 A220747 Adjacent sequences: A025544 A025545 A025546 * A025548 A025549 A025550 KEYWORD easy,nice,nonn AUTHOR Clark Kimberling STATUS approved

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Last modified June 8 10:34 EDT 2023. Contains 363163 sequences. (Running on oeis4.)