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%I #27 Jan 26 2023 12:12:22
%S 3,4,6,8,44,444,888,2222,8888,444444,888888,444444444,888888888,
%T 444444444444,888888888888,222222222222222222,
%U 444444444444444444444444444444,44444444444444444444444444444444
%N Repdigit - 1 is prime.
%C Next term is 88...8 (72 digits).
%C Corresponding values of primes are in A096843. - _Jaroslav Krizek_, Mar 19 2013
%H Patrick De Geest, <a href="http://www.worldofnumbers.com/em83.htm">Repdigits : WONplate 83</a>
%t a[n_]:=NestList[FromDigits[Append[{#},n]]&,n,35]; Union[Join[{3},Flatten[Table[Select[a[n],PrimeQ[#-1]&],{n,2,8,2}]]]] (* _Jayanta Basu_, May 29 2013 *)
%o (PARI) u=30; for(n=1, u, r=(10^n-1)/9; for(a=1, 9, m=r*a; if(ispseudoprime(m-1), print1(m, ", ")))) \\ _Felix Fröhlich_, Jul 07 2014
%Y Cf. A010785.
%K nonn,base
%O 1,1
%A _Patrick De Geest_
%E Offset corrected and initial term added by _Arkadiusz Wesolowski_, Aug 14 2011
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