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A175307
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a(n) = the number of terms in row n of A175306.
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2
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2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 4, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 2, 1, 1, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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a(2n) = 1, and a(3n)=1, for all positive integers n.
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LINKS
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MAPLE
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local R, last, k, P;
R:= n;
last:= n;
P:= n;
while igcd(last, 6)=1 do
for k from last+1 do
if igcd(k-1, P) = 1 and igcd(k, P) = 1 and igcd(k+1, P) =1 then
R:= R, k; last:= k; P:= P*k; break
fi
od
od;
nops([R])
end proc:
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MATHEMATICA
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row[n_] := Module[{R = {n}, last = n, k, P = n}, While[GCD[last, 6] == 1, For[k = last + 1, True, k++, If[GCD[k - 1, P] == 1 && GCD[k, P] == 1 && GCD[k + 1, P] == 1, AppendTo[R, k]; last = k; P = P k; Break[]]]]; R];
a[n_] := Length[row[n]];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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