A271042 a(n) = k is the least squarefree number with a run of n >= 0 nonsquarefree numbers immediately preceding k and a run of zero nonsquarefree numbers immediately succeeding k.

2, 1, 10, 101, 246, 1685, 22026, 217077, 7216626, 8870033, 262315477, 221167433, 105779897634, 82462576233

Offset: 0

Author

Hartmut F. W. Hoft, Mar 29 2016

Keywords

• nonn
• more

Comments

This is the leftmost column (indexed by zero) of the doubly infinite matrix T(i,j) defined in A270996: a(n) = A270996(n*(n+1)/2).

Examples

			a(3) = 101 since 97, 101 and 102 are squarefree while 98, 99 and 100 constitute the first nonsquarefree triple followed by a pair of squarefree numbers.
		

Crossrefs

Cf. A005117, A268330, A270344, A270996.

Programs

Mathematica

(* We use function a270996[] from A270996 *)
Map[a270996[{0, 1000000},{#, 0}]&,Range[0,7]]
(* computes a(0)...a(7) *)

Extensions

a(12)-a(13) from Kevin P. Thompson, Apr 19 2022