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A336323
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Numbers composite(n) such that gcd(n,composite(n)) > 1.
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2
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6, 10, 12, 14, 18, 21, 24, 25, 26, 28, 32, 33, 34, 36, 39, 42, 45, 48, 50, 52, 60, 68, 70, 72, 74, 76, 77, 78, 84, 86, 87, 88, 90, 95, 98, 100, 102, 104, 105, 106, 110, 111, 112, 124, 128, 130, 132, 135, 138, 140, 145, 147, 150, 158, 160, 162, 165, 168, 170
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OFFSET
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1,1
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LINKS
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FORMULA
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MAPLE
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compn:= 0: R:= NULL: count:= 0:
for n from 4 while count < 100 do
if not isprime(n) then
compn:= compn+1;
if igcd(compn, n) > 1 then
R:= R, n; count:= count+1;
fi
fi
od:
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MATHEMATICA
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c = Select[Range[2, 250], ! PrimeQ[#] &]; (* A002808 *)
u = Select[Range[Length[c]], GCD[c[[#]], #] > 1 &] ; (* A334880 *)
Table[c[[u[[n]]]], {n, 1, Length[u]}] (* A336323 *)
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PROG
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(PARI) lista(nn) = {my(n=0, list=List()); forcomposite (c=1, nn, n++; if (gcd(n, c) > 1, listput(list, c))); Vec(list); } \\ Michel Marcus, Jul 19 2020
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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