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 A202104 #15 Aug 26 2025 20:02:36 %S A202104 0,1,3,4,5,8,10,11,14,16,17,21,23,26,30,33,35,37,38,42,43,44,45,47,49, %T A202104 52,56,57,58,59,60,61,63,64,66,72,74,75,77,79,81,85,91,94,96,98,99, %U A202104 100,102,103,105,109,110,113,114,115,127,131,133,134,136,140 %N A202104 Numbers k such that 90*k + 41 is prime. %C A202104 This sequence was generated by adding 12 Fibonacci-like sequences [See: PROG]. Looking at the format 90k+41 modulo 9 and modulo 10 we see that all entries of A142333 have digital root 5 and last digit 1. (Reverting the process is an application of the Chinese remainder theorem.) The 12 Fibonacci-like sequences are generated (via the PERL program) from the base pairs 49*91, 19*59, 37*23, 73*77, 11*61, 29*79, 47*43, 83*7, 13*17, 31*71, 49*89, 67*53. %t A202104 Select[Range[0, 200], PrimeQ[90 # + 41] &] %o A202104 (PARI) is(n)=isprime(90*n+41) \\ _Charles R Greathouse IV_, Feb 17 2017 %Y A202104 Cf. A181732, A198382, A195993, A196000, A196007, A201739, A201734, A201804, A201816, A201817, A201818, A201820, A201822, A202101. %K A202104 nonn,easy,changed %O A202104 1,3 %A A202104 _J. W. Helkenberg_, Dec 11 2011