A026455 a(n) = least positive integer < a(n-1) and not a(i)*a(j)-2 for 1<=i

2, 3, 5, 6, 7, 9, 11, 14, 15, 17, 18, 21, 22, 23, 24, 27, 29, 30, 35, 36, 37, 38, 39, 41, 45, 47, 48, 50, 51, 54, 55, 57, 59, 60, 62, 63, 65, 66, 69, 71, 77, 78, 81, 84, 86, 87, 89, 90, 91, 93, 95, 99, 101, 102, 104, 105, 107, 110, 111, 114

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Comments

Appears to be A026453 shifted once left. - R. J. Mathar, Jul 13 2025

Links

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

Crossrefs

Cf. A026453 and references therein.

Programs

Mathematica

a = {2, 3}; 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 *)