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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.
0
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.
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
KEYWORD
nonn,more
AUTHOR
Hartmut F. W. Hoft, Mar 29 2016
STATUS
approved