OFFSET
1,1
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000
MATHEMATICA
f[n_] := FromDigits @ (Join @@ IntegerDigits[{n, 2n-1}]); Select[f /@ Range[160], PrimeQ] (* Amiram Eldar, Sep 24 2019 *)
PROG
(Magma) [a:m in [1..170]|IsPrime(a) where a is 10^(#Intseq(2*m-1))*m+2*m-1]; // Marius A. Burtea, Oct 09 2019
(Python)
from sympy import isprime
A309851_list = [m for m in (int(str(n)+str(2*n-1)) for n in range(1, 10**5)) if isprime(m)] # Chai Wah Wu, Oct 23 2019
CROSSREFS
KEYWORD
nonn,base
AUTHOR
A.H.M. Smeets, Aug 20 2019
STATUS
approved