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 A217492 #15 Oct 31 2024 06:46:50 %S A217492 0,1,3,4,9,18,49,57,67,69,106,126,258,583,1221,1366,4311,11361,12621, %T A217492 14964,16017,22467,25434,45094,51051,89113 %N A217492 Numbers k such that 9^k + 10 is prime. %C A217492 Contains exactly the halved even terms of A217137. %t A217492 Select[Range[5000], PrimeQ[9^# + 10] &] (* _Vincenzo Librandi_, Oct 05 2012 *) %o A217492 (PARI) is(n)=ispseudoprime(9^n+10) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A217492 Cf. A217137, A217347. %K A217492 nonn,more,hard %O A217492 1,3 %A A217492 _Vincenzo Librandi_, Oct 05 2012 %E A217492 a(18)-a(26) added from the data at A217137 by _Amiram Eldar_, Jun 19 2022