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A175306
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Irregular array: row n contains A175307(n) terms. The first term of each row, a(n,1) = n. a(n,m) = the smallest integer > a(n,m-1) such that a(n,m), a(n,m)-1, and a(n,m)+1 are each coprime to all earlier terms in their row. The row terminates when a multiple of 2 or 3 is obtained.
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2
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1, 2, 2, 3, 4, 5, 7, 12, 6, 7, 9, 8, 9, 10, 11, 13, 15, 12, 13, 15, 14, 15, 16, 17, 19, 21, 18, 19, 21, 20, 21, 22, 23, 25, 27, 24, 25, 27, 26, 27, 28, 29, 31, 33, 30, 31, 33, 32, 33, 34, 35, 37, 47, 52, 36, 37, 39, 38, 39, 40, 41, 43, 45, 42, 43, 45, 44, 45, 46, 47, 49, 51, 48, 49, 51, 50, 51, 52, 53
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OFFSET
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1,2
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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;
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];
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CROSSREFS
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KEYWORD
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nonn,tabf
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AUTHOR
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STATUS
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approved
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