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A145851 Primes of the form k followed by k 9's. 2

%I

%S 19,49999,599999,1799999999999999999,2099999999999999999999,

%T 289999999999999999999999999999

%N Primes of the form k followed by k 9's.

%C Corresponding k, which cannot be multiples of 3, are in A174352. The next term has 176 digits, too large to include here. - _Rick L. Shepherd_, Mar 22 2010

%o (PARI) lista(nn) = for(k=1, nn, if(ispseudoprime(q=k*10^(k-1)-1), print1(q, ", "))); \\ _Jinyuan Wang_, Mar 24 2020

%Y Cf. A141311, A145852.

%Y Cf. A174352. - _Rick L. Shepherd_, Mar 22 2010

%K nonn,base

%O 1,1

%A _Lekraj Beedassy_, Oct 21 2008

%E a(2) was 4999; corrected by _Rick L. Shepherd_, Mar 22 2010

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Last modified June 17 13:43 EDT 2021. Contains 345080 sequences. (Running on oeis4.)