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A007731
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a(n) = a(floor(n/2)) + a(floor(n/3)) + a(floor(n/6)).
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8
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1, 3, 5, 7, 9, 9, 15, 15, 17, 19, 19, 19, 29, 29, 29, 29, 31, 31, 41, 41, 41, 41, 41, 41, 55, 55, 55, 57, 57, 57, 57, 57, 59, 59, 59, 59, 85, 85, 85, 85, 85, 85, 85, 85, 85, 85, 85, 85, 103, 103, 103, 103, 103, 103, 117, 117
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graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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LINKS
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FORMULA
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From given link, a(n) is asymptotic to c*n where c = 12/log(432) = 1.97744865... - Benoit Cloitre, Dec 18 2002
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MAPLE
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A007731 := proc(n) option remember; if n=0 then RETURN(1) else RETURN( A007731(trunc(n/2))+A007731(trunc(n/3))+A007731(trunc(n/6))); fi; end;
# second Maple program:
a:= proc(n) option remember; `if`(n=0, 1,
add(a(floor(n/i)), i=[2, 3, 6]))
end:
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MATHEMATICA
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a[n_] := a[n] = a[Floor[n/2]] + a[Floor[n/3]] + a[Floor[n/6]] ; a[0] = 1; Table[a[n], {n, 0, 60}] (* Jean-François Alcover, Mar 06 2014 *)
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PROG
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(Haskell)
a007731 n = a007731_list !! n
a007731_list = 1 : (zipWith3 (\u v w -> u + v + w)
(map (a007731 . (`div` 2)) [1..])
(map (a007731 . (`div` 3)) [1..])
(map (a007731 . (`div` 6)) [1..]))
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CROSSREFS
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KEYWORD
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nonn,easy,nice
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AUTHOR
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STATUS
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approved
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