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

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

Links

Table of n, a(n) for n=1..6.

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. A141311, A145852.

Cf. A174352. - Rick L. Shepherd, Mar 22 2010

Sequence in context: A203703 A068734 A216529 * A182374 A034207 A098970

Adjacent sequences: A145848 A145849 A145850 * A145852 A145853 A145854

Keyword

nonn,base

Author

Lekraj Beedassy, Oct 21 2008

Extensions

a(2) was 4999; corrected by Rick L. Shepherd, Mar 22 2010

Status

approved