OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(3) = 41 is in the sequence because 41 and 4241 are primes.
MAPLE
select(t -> isprime(t) and isprime(10^(1+ilog10(t))*(t+1)+t), [$1..20000]);
MATHEMATICA
Select[Prime[Range[350]], PrimeQ[(#+1)10^IntegerLength[#]+#]&] (* Harvey P. Dale, May 07 2022 *)
PROG
(Magma) [p:p in PrimesUpTo(2200)| IsPrime(Seqint(Intseq(p) cat Intseq(p+1)))]; // Marius A. Burtea, Aug 23 2019
(PARI) isok(k) = isprime(k) && isprime(eval(Str(k+1, k))); \\ Jinyuan Wang, Aug 26 2019
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Robert Israel, Aug 23 2019
STATUS
approved