A026457 a(n) = least positive integer < a(n-1) and not a(i)*a(j)-2 for 1<=i

2, 4, 5, 7, 9, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 25, 27, 29, 30, 31, 35, 37, 39, 41, 45, 46, 47, 49, 51, 55, 57, 59, 62, 64, 65, 67, 69, 70, 71, 77, 78, 79, 81, 84, 85, 87, 91, 94, 95, 99, 101, 102, 104, 105, 107, 109, 110, 111, 119

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Links

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

Crossrefs

Cf. A026453 and references therein.

Programs

Mathematica

a = {2, 4}; 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 *)