A026456 a(n) = least positive integer < a(n-1) and not a(i)*a(j)-2 for 1<=i<j<=n.

1, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, 20, 21, 23, 24, 25, 27, 29, 31, 32, 35, 36, 37, 39, 41, 44, 45, 47, 49, 51, 55, 56, 57, 59, 60, 65, 67, 69, 71, 72, 77, 79, 80, 81, 84, 85, 87, 91, 92, 95, 99, 101, 104, 105, 107

Offset

1,2

Links

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

Mathematica

a = {1, 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 *)

Crossrefs

Cf. A026453 and references therein.

Sequence in context: A026419 A026434 A181708 * A026425 A026440 A299487

Adjacent sequences: A026453 A026454 A026455 * A026457 A026458 A026459

Keyword

nonn

Author

Clark Kimberling

Status

approved