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A372748 a(1) = 3; for n > 1, a(n) = a(n - 1) if GCD(n - 1, a(n - 1)) = 1, otherwise a(n) = n - 1 - a(n - 1) / GCD(n - 1, a(n - 1)). 1
3, 3, 3, 2, 3, 3, 5, 5, 5, 5, 9, 9, 9, 9, 9, 12, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 25, 25, 25, 25, 25, 25, 25, 25, 25, 30, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 61, 61, 61, 61, 61, 61, 61, 61 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(n) = n/2 for n from {4,6,10,26,62,122,298,626,1094,2186,...}.
LINKS
EXAMPLE
a(1) = 3.
a(2) = 3 because GCD(1,3) = 1.
a(3) = 3 because GCD(2,3) = 1.
a(4) = 3 - 3/GCD(3,3) = 2.
and so on.
MATHEMATICA
Block[{n = 0}, NestList[If[CoprimeQ[++n, #], #, n - #/GCD[n, #]] &, 3, 100]] (* Paolo Xausa, May 12 2024 *)
CROSSREFS
Sequence in context: A226895 A306996 A166007 * A087497 A085767 A082127
KEYWORD
nonn
AUTHOR
Ctibor O. Zizka, May 12 2024
STATUS
approved

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Last modified June 15 19:43 EDT 2024. Contains 373410 sequences. (Running on oeis4.)