A271041 a(n) = k is the least squarefree number with a run of zero nonsquarefree numbers immediately preceding k and a run of exactly n>=0 nonsquarefree numbers immediately succeeding k.

2, 3, 7, 47, 8474, 843, 22019, 826823, 1092746, 33908367, 262315466

Offset

0,1

Comments

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

a(11) = T(0,11) > 3*10^9.

Links

Table of n, a(n) for n=0..10.

Example

a(3) = 47 since 46, 47 and 51 are squarefree while 48, 49 and 50 constitute the first nonsquarefree triple after a pair of squarefree numbers.

Mathematica

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

Crossrefs

Cf. A005117, A268330, A270344, A270996.

Sequence in context: A274385 A075461 A059785 * A270402 A253574 A343557

Adjacent sequences: A271038 A271039 A271040 * A271042 A271043 A271044

Keyword

nonn,more

Author

Hartmut F. W. Hoft, Mar 29 2016

Status

approved