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 A158806 #13 Apr 05 2025 11:17:01 %S A158806 0,2,3,4,6,7,11,12,13,14,16,20,23,24,25,27,28,30,33,34,35,37,41,42,46, %T A158806 47,48,49,51,52,53,55,56,58,59,62,66,67,69,72,74,75,79,84,88,89,90,91, %U A158806 100,101,102,103,105,107,108,110,115,116,117,118,123,124,125,129,130 %N A158806 Numbers n such that 30*n + 19 is prime. %C A158806 Encoded primes with LSD 9, (SOD-1)/3 integer, (LSD, least significant digit; SOD, sum of digits). Divide any such number by 30, if the whole number portion of the quotient is in the sequence, the number is prime. %H A158806 Harvey P. Dale, <a href="/A158806/b158806.txt">Table of n, a(n) for n = 1..1000</a> %F A158806 a(n) = (A132234(n) - 19)/30 = Floor[A132234(n)/30]. - Chandler %e A158806 Example: 3019, with LSD 9, (SOD-1)/3 integer; Then 3019/30 = 100.633, or 100, which is in the sequence, thus 3019 is prime. %t A158806 Select[Range[0,150],PrimeQ[30#+19]&] (* _Harvey P. Dale_, Apr 05 2025 *) %o A158806 (PARI) is(n)=isprime(30*n+19) \\ _Charles R Greathouse IV_, Feb 17 2017 %Y A158806 Cf. A111175, A158573, A158614, A158648, A158746, A158791, A158850. %K A158806 nonn %O A158806 1,2 %A A158806 _Ki Punches_, Mar 27 2009 %E A158806 Edited by _Ray Chandler_, Apr 07 2009