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%I #15 Jun 29 2019 12:32:07
%S 561,8911,75361,997633,9890881,99861985,993905641,9999109081,
%T 99976607641,999629786233,9999501351841,99994742993377,
%U 999922265173441,9999924433632001,99999201310035841,999996386511276505,9999998594193164041
%N Largest n-digit Carmichael numbers.
%e a(4)=8911 because 8911 is the largest 4-digit Carmichael number. [corrected by _Jon E. Schoenfield_, Jan 28 2014]
%t CarmichaelNbrQ[n_] := !PrimeQ[n] && Mod[n, CarmichaelLambda[n]] == 1; f[n_] := f[n] = Block[{k = 10^n - 1}, While[!CarmichaelNbrQ[k], k -= 2]; k]; Reap[Do[Print[{n, f[n]}]; Sow[f[n]], {n, 3, 10}]][[2, 1]] (* _Jean-François Alcover_, Jan 28 2014, after _Shyam Sunder Gupta_ *)
%Y Cf. A062568, A062852, A048123.
%K hard,more,nonn,base
%O 3,1
%A _Shyam Sunder Gupta_, Feb 17 2002
%E a(17)-a(19) from _Amiram Eldar_, Jun 29 2019