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 A201820 #20 Sep 08 2022 08:46:01 %S A201820 0,1,3,4,6,7,8,11,12,13,14,15,17,19,20,21,22,25,28,29,32,34,39,40,42, %T A201820 45,47,50,52,53,55,57,59,63,64,67,68,70,76,78,84,85,87,90,95,96,97,99, %U A201820 102,103,105,108,109,110,112,113,116,119,122,123,125,129,131 %N A201820 Numbers k such that 90*k + 23 is prime. %C A201820 This sequence was generated by adding 12 Fibonacci-like sequences. Looking at the format 90*k+23 modulo 9 and modulo 10 we see that all entries of A142324 have digital root 5 and last digit 3. (Reverting the process is an application of the Chinese remainder theorem.) %H A201820 Vincenzo Librandi, <a href="/A201820/b201820.txt">Table of n, a(n) for n = 1..10000</a> %F A201820 a(n) = (A142324(n) - 23)/90. %t A201820 Select[Range[0,400],PrimeQ[90 #+23]&] (* _Vincenzo Librandi_, Dec 11 2011 *) %o A201820 (Magma) [n: n in [0..200] | IsPrime(90*n+23)]; // _Vincenzo Librandi_, Dec 11 2011 %o A201820 (PARI) is(n)=isprime(90*n+23) \\ _Charles R Greathouse IV_, Feb 17 2017 %Y A201820 Cf. A181732, A198382, A195993, A196000, A196007, A201739, A201734, A201804, A201816, A201817, A201818. %K A201820 nonn,easy %O A201820 1,3 %A A201820 _J. W. Helkenberg_, Dec 05 2011