OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
filter:= n -> isprime(n*(10^(1+ilog10(n+4))+1)+4):
select(filter, [seq(i, i=1..1000, 2)]); # Robert Israel, Nov 14 2019
MATHEMATICA
prkk4Q[k_]:=With[{c=k+4}, PrimeQ[k*10^IntegerLength[c]+c]]; Select[ Range[ 600], prkk4Q] (* Harvey P. Dale, Aug 31 2021 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, May 15 1998
STATUS
approved