Module[{nn=50, odds}, odds=Range[1, 2nn+1, 2]; Position[Table[ FromDigits[ Flatten[IntegerDigits/@Take[odds, n]]], {n, nn}], _?(PrimeQ[#]&)]]// Flatten (* The program generates the first 5 terms of the sequence. To generate the 6th, increase the value of nn to 2570 or more, but the program will take a long time to run. *) (*
Harvey P. Dale, Jul 21 2021 *)