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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Alois P. Heinz, Table of n, a(n) for n = 1..10000

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-Fran├žois Alcover, Mar 27 2017, after Alois P. Heinz *)

CROSSREFS

Cf. A211384.

Sequence in context: A124874 A230258 A016459 * A275663 A060585 A114451

Adjacent sequences:  A242306 A242307 A242308 * A242310 A242311 A242312

KEYWORD

nonn,look

AUTHOR

J. Lowell, May 10 2014

EXTENSIONS

More terms from Alois P. Heinz, May 10 2014

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 1 17:45 EDT 2020. Contains 337444 sequences. (Running on oeis4.)