A145852 Primes of the form k followed by a 0 and k 9's.

109, 2099, 409999, 1909999999999999999999, 2809999999999999999999999999999, 41099999999999999999999999999999999999999999, 7609999999999999999999999999999999999999999999999999999999999999999999999999999

Offset: 1

Author

Lekraj Beedassy, Oct 21 2008

Keywords

• nonn

Comments

Primes of the form k*10^(k+1) + 10^k - 1.

Crossrefs

Cf. A141311, A145851.

Programs

PARI

lista(nn) = for(k=1, nn, if(ispseudoprime(q=k*10^(k+1)+10^k-1), print1(q, ", "))); \\ Jinyuan Wang, Mar 24 2020