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%I #13 Jan 19 2019 04:15:43
%S 2,3,7,47,8474,843,22019,826823,1092746,33908367,262315466
%N 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.
%C 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).
%C a(11) = T(0,11) > 3*10^9.
%e 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.
%t (* We use function a270996[] from A270996 *)
%t Map[a270996[{0, 1000000},{0, #}]&,Range[0,7]]
%t (* computes a(0)...a(7) *)
%Y Cf. A005117, A268330, A270344, A270996.
%K nonn,more
%O 0,1
%A _Hartmut F. W. Hoft_, Mar 29 2016