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A242309 a(n) = A211384(2n)/A211384(n). 1
3, 2, 3, 3, 3, 2, 3, 4, 6, 6, 9, 9, 9, 8, 6, 5, 6, 4, 6, 7, 6, 5, 6, 6, 6, 8, 8, 9, 12, 12, 12, 14, 13, 12, 15, 18, 18, 12, 18, 20, 21, 20, 21, 21, 21, 20, 21, 20, 21, 24, 24, 20, 27, 26, 27, 20, 20, 16, 18, 21, 21, 21, 19, 18, 27, 30, 33, 33, 33, 48, 51, 42 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
a(11) = 9 because A211384(22) = 198 and A211384(11) = 22 and 198/22 = 9.
MAPLE
b:= proc(n) b(n):= `if`(n<3, 2*n-1, (h-> ceil((b(n-1)+1)/h)*h)
(ilcm(map(b, numtheory[divisors](n) minus {1, n})[]))) end:
a:= n-> b(2*n)/b(n):
seq(a(n), n=1..100); # Alois P. Heinz, May 20 2014
MATHEMATICA
b[1] = 1; b[2] = 3; b[n_] := b[n] = (Ceiling[(b[n-1]+1)/#]*#&)[LCM @@ Map[b, Most[Divisors[n]]]];
a[n_] := b[2n]/b[n];
Table[a[n], {n, 1, 80}] (* Jean-François Alcover, Mar 27 2017, after Alois P. Heinz *)
CROSSREFS
Cf. A211384.
Sequence in context: A124874 A230258 A016459 * A275663 A369100 A060585
KEYWORD
nonn,look
AUTHOR
J. Lowell, May 10 2014
EXTENSIONS
More terms from Alois P. Heinz, May 10 2014
STATUS
approved

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Last modified May 19 00:35 EDT 2024. Contains 372666 sequences. (Running on oeis4.)