A108816 Primes of the form n*10^x+n+1, where 0 < n < 9, x=0,1,2..

3, 5, 7, 11, 13, 17, 23, 67, 89, 607, 809, 2003, 6007, 8009, 200003, 2000003, 8000009, 20000003, 600000007, 6000000007, 2000000000003, 8000000000009, 20000000000000003, 200000000000000003, 60000000000000000007

Offset

1,1

Links

Table of n, a(n) for n=1..25.

Example

n=2,x=3. a(x,n) = 2*10^3+2+1 = 2003 prime.

Mathematica

Select[Union[Flatten[Table[n*10^x+n+1, {n, 8}, {x, 0, 20}]]], PrimeQ] (* Harvey P. Dale, Jul 09 2020 *)

Prog

(PARI) n10np1(n) = { local(x, y, k); for(x=0, n, for(k=1, 8, y=10^x*k+k+1; if(isprime(y), print1(y", ")) ) ) }

Crossrefs

Sequence in context: A154868 A274987 A020628 * A088503 A118939 A239391

Adjacent sequences: A108813 A108814 A108815 * A108817 A108818 A108819

Keyword

nonn

Author

Cino Hilliard, Jul 10, 2005

Status

approved