OFFSET
1,3
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
MATHEMATICA
1/2*Differences@ Select[Prime@ Range[300], PrimeQ[10^(1 + Floor@ Log10[#]) - #] &] (* Michael De Vlieger, Dec 18 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 18 2022
STATUS
approved