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 A073499 #31 Apr 13 2025 07:53:15
%S A073499 1,2,80,342,848,1194,2658,4790,9376
%N A073499 Numbers k such that k^(k+1) + (k+1)^k is prime.
%C A073499 a(10) > 20000. - _Michael S. Branicky_, Apr 13 2025
%H A073499 P. Leyland, <a href="http://www.leyland.vispa.com/numth/primes/xyyx.htm">Primes and Strong Pseudoprimes of the form x^y + y^x</a> - The numbers corresponding to the first 7 terms had been proved prime by 2005.
%e A073499 1^2 + 2^1 = 3 and 2^3 + 3^2 = 17 are the primes corresponding to the first two terms. The next five terms correspond to primes of 155, 870, 2487, 3678 and 9106 decimal digits.
%t A073499 Do[ If[ PrimeQ[n^(n + 1) + (n + 1)^n], Print[n]], {n, 1, 1650}]
%o A073499 (PARI) for(n=1,1650, if(isprime((n^(n+1))+((n+1)^n)), print1(n,",")))
%Y A073499 Cf. A072179, A051442, A094133.
%K A073499 nonn,hard,more
%O A073499 1,2
%A A073499 _Rick L. Shepherd_, Aug 05 2002
%E A073499 Edited by _Robert G. Wilson v_, Aug 08 2002
%E A073499 a(7) from _Charles R Greathouse IV_, Jan 13 2012
%E A073499 a(8) from _Charles R Greathouse IV_, Jan 17 2012
%E A073499 a(9) found by _Alexander Adamchuk_, Apr 09 2007 and shown to be a(9) by _Charles R Greathouse IV_, Jan 27 2012