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A145851
Primes of the form k followed by k 9's.
2
19, 49999, 599999, 1799999999999999999, 2099999999999999999999, 289999999999999999999999999999
OFFSET
1,1
COMMENTS
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
MATHEMATICA
Select[Table[FromDigits[PadRight[{k}, k+1, 9]], {k, 200}], PrimeQ] (* Harvey P. Dale, Jun 22 2022 *)
PROG
(PARI) lista(nn) = for(k=1, nn, if(ispseudoprime(q=k*10^(k-1)-1), print1(q, ", "))); \\ Jinyuan Wang, Mar 24 2020
CROSSREFS
Cf. A174352. - Rick L. Shepherd, Mar 22 2010
Sequence in context: A203703 A068734 A216529 * A182374 A034207 A098970
KEYWORD
nonn,base
AUTHOR
Lekraj Beedassy, Oct 21 2008
EXTENSIONS
a(2) was 4999; corrected by Rick L. Shepherd, Mar 22 2010
STATUS
approved