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A026426 a(n) = least positive integer > a(n-1) and not a(i)*a(j) for 1<=i<=j<=n, n >= 2. 2
2, 4, 5, 6, 7, 9, 11, 13, 15, 17, 19, 21, 23, 27, 29, 31, 32, 33, 37, 39, 40, 41, 43, 47, 48, 50, 51, 53, 56, 57, 59, 61, 67, 69, 70, 71, 72, 73, 79, 83, 87, 88, 89, 93, 97, 98, 101, 103, 104, 107, 109, 110, 111, 113, 120, 123, 125, 127 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..1000

MATHEMATICA

a = {2, 4}; used = {a[[1]]^2, a[[1]]*a[[2]], a[[2]]^2}; Do[k = a[[-1]] + 1; While[MemberQ[used, k], k++]; AppendTo[a, k]; used = Union[used, k*a], {n, 3, 66}]; a (* Ivan Neretin, Mar 07 2016 *)

CROSSREFS

Cf. A026416 and references therein.

Sequence in context: A026420 A026479 A242788 * A026480 A126424 A164317

Adjacent sequences:  A026423 A026424 A026425 * A026427 A026428 A026429

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified November 21 09:56 EST 2019. Contains 329362 sequences. (Running on oeis4.)