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 A118841 #38 Feb 16 2025 08:33:01 %S A118841 1,2,3,4,8,16 %N A118841 Numbers k such that ceiling(phi^k) is prime. %C A118841 a(7) if it exists is greater than 250000. - _Mark Rodenkirch_, Feb 22 2020 %H A118841 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Phi-Prime.html">Phi-Prime</a> %t A118841 Select[Range[20],PrimeQ[Ceiling[GoldenRatio^#]]&] (* _James C. McMahon_, Sep 14 2024 *) %o A118841 (PARI) c(n) = 3*fibonacci(n-1) + fibonacci(n-2) + (n % 2); \\ A169986(n) for n >= 1 %o A118841 for(n=1,10^7,if(ispseudoprime(c(n)),print1(n,", "))) %o A118841 \\ _Joerg Arndt_, Feb 22 2020 %Y A118841 Cf. A118842, A001606. %K A118841 nonn %O A118841 1,2 %A A118841 _Eric W. Weisstein_, May 01 2006 %E A118841 a(7)-a(8) from _Charles R Greathouse IV_, Jul 30 2011 %E A118841 a(9)-a(11) from _Charles R Greathouse IV_, Aug 01 2011 %E A118841 Incorrect a(7)-a(11) removed by _Mark Rodenkirch_, Feb 22 2020