This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A050805 #16 Aug 04 2021 13:27:39
%S A050805 439,853,1013,1061,1109,1117,1153,1187,1213,1249,1259,1283,1291,1301,
%T A050805 1303,1361,1427,1451,1489,1511,1523,1531,1583,1597,1607,1657,1733,
%U A050805 1747,1753,1801,1873,1879,1913,1951,2069,2083,2137,2243,2251,2267,2293,2297
%N A050805 Inserting any digit between adjacent digits of prime p never yields another prime.
%H A050805 Reinhard Zumkeller, <a href="/A050805/b050805.txt">Table of n, a(n) for n = 1..10000</a>
%e A050805 40309, 41319, 42327, 43339, 44349, 45359, 46369, 47379, 48389, and 49399 are all composite. Thus, 439, being prime, belongs to the sequence.
%t A050805 a[n_]:=Or@@PrimeQ[Table[FromDigits[Riffle[IntegerDigits[n],k]],{k,0,9}]]; Select[Prime[Range[5,350]],a[#]==False&] (* _Jayanta Basu_, May 30 2013 *)
%t A050805 Select[Prime[Range[400]],NoneTrue[Table[FromDigits[Riffle[ IntegerDigits[ #],d]],{d,0,9}],PrimeQ]&] (* _Harvey P. Dale_, Aug 04 2021 *)
%o A050805 (Haskell)
%o A050805 import Data.List (intersperse)
%o A050805 a050805 n = a050805_list !! (n-1)
%o A050805 a050805_list = filter ((all (== 0)) . f) a000040_list where
%o A050805 f p = map (i $ show p) "0123456789"
%o A050805 i ps d = a010051' (read $ intersperse d ps :: Integer)
%o A050805 -- _Reinhard Zumkeller_, May 07 2013
%Y A050805 Cf. A050674-A050719, A050806.
%Y A050805 Cf. A010051, A000040.
%K A050805 nonn,nice,base
%O A050805 1,1
%A A050805 _Patrick De Geest_, Oct 15 1999
%E A050805 Offset corrected by _Reinhard Zumkeller_, May 07 2013