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A025547
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Least common multiple of {1,3,5,...,2n-1}.
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34
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1, 3, 15, 105, 315, 3465, 45045, 45045, 765765, 14549535, 14549535, 334639305, 1673196525, 5019589575, 145568097675, 4512611027925, 4512611027925, 4512611027925, 166966608033225, 166966608033225, 6845630929362225, 294362129962575675, 294362129962575675
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OFFSET
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1,2
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COMMENTS
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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.
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LINKS
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MAPLE
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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!
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MATHEMATICA
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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 *)
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PROG
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(Haskell)
a025547 n = a025547_list !! (n-1)
a025547_list = scanl1 lcm a005408_list
(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))
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CROSSREFS
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KEYWORD
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easy,nice,nonn
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AUTHOR
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STATUS
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approved
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