A271042 - OEIS

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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

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OFFSET

0,1

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).

LINKS

Table of n, a(n) for n=0..13.

EXAMPLE

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.

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: A213421 A370068 A239070 * A098290 A160110 A258055

Adjacent sequences: A271039 A271040 A271041 * A271043 A271044 A271045

KEYWORD

nonn,more

AUTHOR

Hartmut F. W. Hoft, Mar 29 2016

EXTENSIONS

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

STATUS

approved