A026459 Erroneous version of A026461.
1, 2, 3, 5, 6, 9, 11, 12, 14, 15, 17, 18, 19, 21, 24, 27, 29, 30, 33, 35, 37, 38
Offset: 1
This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
After the terms 1, 2, 3, 5, 6, 7, we can get 8 from 2*5 - 2, but not 9 (11 is not a product of two distinct terms from {1, 2, 3, 5, 6, 7}), so a(7) = 9. - _N. J. A. Sloane_, Aug 06 2021
a = {1, 2}; used = {a[[1]]*a[[2]] - 2}; Do[k = a[[-1]] + 1; While[MemberQ[used, k], k++]; used = Union[used, k*a - 2]; AppendTo[a, k], {n, 3, 60}]; a (* Ivan Neretin, Mar 06 2016 *)