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A151546 When computing A160256(n), it must be a multiple of a(n). 2

%I #11 Jun 11 2018 11:53:06

%S 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,

%T 420,11,420,11,420,11,420,11,420,11,420,11,420,11,420,22,378,55,126,

%U 55,63,220,63,440,189,880,567,880,189,220,63,55,252,275,252,275,336,275,84,275,84

%N When computing A160256(n), it must be a multiple of a(n).

%C In other words, a(n) = numerator of b(n-2)/b(n-1), where b() = A160256().

%C Then b(n) = smallest multiple of a(n) not already present in A160256.

%H Alois P. Heinz, <a href="/A151546/b151546.txt">Table of n, a(n) for n = 3..10000</a>

%p 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

%t bb[n_] := bb[n] = False;

%t 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 ]];

%t a[n_] := Numerator[b[n - 2] /b[n - 1]];

%t Table[a[n], {n, 3, 100}]

%K nonn,look

%O 3,2

%A _N. J. A. Sloane_, May 16 2009

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Last modified April 24 22:17 EDT 2024. Contains 371964 sequences. (Running on oeis4.)