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 A050714 #15 Nov 03 2024 19:40:47 %S A050714 19,21,37,39,43,49,51,57,61,63,67,73,91,97,113,119,123,129,131,137, %T A050714 147,149,153,159,171,177,183,197,203,209,227,243,257,279,281,287,293, %U A050714 311,317,353,359,369,377,381,383,387,389,399,401,429,449,453,459,461,467 %N A050714 Inserting a digit '4' between adjacent digits of n makes a prime. %H A050714 Harvey P. Dale, <a href="/A050714/b050714.txt">Table of n, a(n) for n = 1..1000</a> %e A050714 389 becomes 3(4)8(4)9 which is prime 34849. %t A050714 Select[Range[10,500],PrimeQ[FromDigits[Riffle[IntegerDigits[#],4]]]&] (* _Harvey P. Dale_, Nov 03 2024 *) %Y A050714 Cf. A050674, A050711, A050712, A050713, A050715, A050716, A050717, A050718, A050719. %K A050714 nonn,base %O A050714 1,1 %A A050714 _Patrick De Geest_, Aug 15 1999