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 A165444 #9 Apr 03 2023 10:36:11 %S A165444 43,47,419,431,443,461,467,479,4127,4139,4157,4211,4229,4241,4271, %T A165444 4283,4337,4349,4373,4397,4409,4421,4457,4463,4523,4547,4643,4673, %U A165444 4691,4733,4751,4787,4877,4919,4937,4967,41039,41051,41117,41201,41213,41231,41381,41399 %N A165444 Primes obtained from other primes by prefixing a 4. %H A165444 Harvey P. Dale, <a href="/A165444/b165444.txt">Table of n, a(n) for n = 1..1000</a> %H A165444 Chris Caldwell, <a href="https://t5k.org/lists/small/10000.txt">The First 10,000 Primes</a> %e A165444 4547 is a prime obtained by prefixing a 4 to the prime 547. %t A165444 Select[4*10^IntegerLength[#]+#&/@Prime[Range[300]],PrimeQ] (* _Harvey P. Dale_, Mar 25 2016 *) %Y A165444 Cf. A000040, A165243, A165292 %K A165444 base,nonn %O A165444 1,1 %A A165444 _Parthasarathy Nambi_, Sep 19 2009 %E A165444 More terms from _Vincenzo Librandi_, Sep 20 2009