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 A103234 #42 Feb 16 2025 08:32:56 %S A103234 4,6,38,454,510 %N A103234 Numbers k such that the k-th Euler number (A122045(k)) is prime. %C A103234 Equals 2*A014547. %C A103234 No others for k <= 69574 (Simon Plouffe). - _Eric W. Weisstein_, Aug 24 2020 %C A103234 No others for k <= 112130 (Simon Plouffe). - _Eric W. Weisstein_, Apr 15 2024 %H A103234 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/EulerNumber.html">Euler Number</a> %H A103234 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/EulerNumberPrime.html">Euler Number Prime</a> %H A103234 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IntegerSequencePrimes.html">Integer Sequence Primes</a> %t A103234 Position[EulerE[Range[600]], _?PrimeQ] // Flatten %t A103234 Select[Range[600], PrimeQ @* EulerE] (* _Eric W. Weisstein_, Apr 12 2024 *) %Y A103234 Cf. A000364, A014547, A122045 (EulerE), A092823. %K A103234 nonn,hard,more %O A103234 1,1 %A A103234 _Eric W. Weisstein_, Jan 26 2005