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A151546
When computing A160256(n), it must be a multiple of a(n).
2
1, 2, 3, 2, 3, 8, 9, 8, 3, 2, 6, 1, 6, 5, 12, 5, 12, 1, 60, 7, 60, 7, 60, 7, 60, 7, 60, 7, 60, 1, 420, 11, 420, 11, 420, 11, 420, 11, 420, 11, 420, 11, 420, 11, 420, 22, 378, 55, 126, 55, 63, 220, 63, 440, 189, 880, 567, 880, 189, 220, 63, 55, 252, 275, 252, 275, 336, 275, 84, 275, 84
OFFSET
3,2
COMMENTS
In other words, a(n) = numerator of b(n-2)/b(n-1), where b() = A160256().
Then b(n) = smallest multiple of a(n) not already present in A160256.
LINKS
MAPLE
bb:= proc(n) option remember; false end: b:= proc(n) option remember; local k, m; if n<3 then bb(n):= true; n else m:= denom(b(n-1) /b(n-2)); for k from m by m while bb(k) do od; bb(k):= true; k fi end: a:= n-> numer(b(n-2) /b(n-1)): seq(a(n), n=3..100); # Alois P. Heinz, May 17 2009
MATHEMATICA
bb[n_] := bb[n] = False;
b[n_] := b[n] = Module[{k, m}, If[n < 3, bb[n] = True; n, m = Denominator[ b[n - 1] /b[n - 2]]; For[ k = m , bb[k], k += m]; bb[k] = True; k ]];
a[n_] := Numerator[b[n - 2] /b[n - 1]];
Table[a[n], {n, 3, 100}]
CROSSREFS
Sequence in context: A085216 A300663 A102310 * A117936 A264766 A251090
KEYWORD
nonn,look
AUTHOR
N. J. A. Sloane, May 16 2009
STATUS
approved