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 A026481 a(n) = least positive integer > a(n-1) and not a(i)*a(j)*a(k) for 1<=i
 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 16, 17, 19, 22, 23, 25, 26, 29, 31, 34, 37, 38, 41, 43, 46, 47, 49, 53, 58, 59, 61, 62, 67, 71, 73, 74, 79, 81, 82, 83, 86, 89, 94, 97, 101, 103, 106, 107, 109, 113, 118, 121, 122, 127, 131, 134, 137, 139, 142, 146, 149, 151, 157 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS MATHEMATICA a = {1, 3, 4}; no = {1 3 4}; Do[x = SelectFirst[Range[Last[a] + 1, 1000], ! MemberQ[no, #] &]; AppendTo[a, x]; no = Union[Times @@@ Subsets[a, {3}]], 62]; a (* Robert Price, May 26 2019 *) CROSSREFS There are six related sequences: A026477: 1 <= i <  j <  k < n  starting 1,2,3; A026478: 1 <= i <= j <= k < n  starting 1,2,3; A026479: 1 <= i <  j <  k < n  starting 1,2,4; A026480: 1 <= i <= j <= k < n  starting 1,2,4; A026481: 1 <= i <  j <  k < n  starting 1,3,4; A026482: 1 <= i <= j <= k < n  starting 1,3,4. Sequence in context: A298112 A026417 A026421 * A039211 A114035 A329779 Adjacent sequences:  A026478 A026479 A026480 * A026482 A026483 A026484 KEYWORD nonn,easy AUTHOR EXTENSIONS More terms from Todd Will (towill(AT)davidson.edu). STATUS approved

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Last modified March 30 12:10 EDT 2020. Contains 333125 sequences. (Running on oeis4.)