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A026422
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a(n) = least positive integer > a(n-1) and not a(i)*a(j) for 1<=i<=j<=n.
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1
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1, 2, 3, 5, 7, 8, 11, 12, 13, 17, 18, 19, 20, 23, 27, 28, 29, 30, 31, 32, 37, 41, 42, 43, 44, 45, 47, 48, 50, 52, 53, 59, 61, 63, 66, 67, 68, 70, 71, 72, 73, 75, 76, 78, 79, 80, 83, 89, 92, 97, 98, 99, 101, 102, 103, 105, 107, 108, 109, 110
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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MATHEMATICA
| a[1]=1; a[n_] := a[n] = (t= Union[Flatten[Table[a[i] a[j], {i, 1, n-1}, {j, i, n-1}]]]; Do[If[FreeQ[t, k], an = k; Break[]], {k, a[n-1]+1, Last[t]+1}]; an); Array[a, 60] (* From Jean-François Alcover, May 6 2011 *)
Select[Range[110], OddQ[Total[FactorInteger[#]][[2]]] &] (* T. D. Noe, May 07 2011 *)
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CROSSREFS
| Apart from initial term, same as A026424.
Sequence in context: A082634 A100959 A166982 * A026424 A141832 A066680
Adjacent sequences: A026419 A026420 A026421 * A026423 A026424 A026425
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KEYWORD
| nonn
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AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu)
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