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 A075469 #21 Feb 21 2025 05:22:09 %S A075469 1,20,253,3122,46651,823540,16777155,387420478,9999999939, %T A075469 285311670528,8916100448227,302875106592216,11112006825558003, %U A075469 437893890380859368,18446744073709551537,827240261886336764070,39346408075296537575383 %N A075469 Maximal m such that n^n-m and n^n+m are both primes, or -1 if there is no such m. %C A075469 Are there any negative terms? %C A075469 Of course the Goldbach conjecture implies that the answer is "no"; further, the first thousand terms are positive. - _Charles R Greathouse IV_, Mar 16 2016 %H A075469 Charles R Greathouse IV, <a href="/A075469/b075469.txt">Table of n, a(n) for n = 2..386</a> %F A075469 a(n) = A047949(n^n). - _Michel Marcus_, Jun 09 2013 %e A075469 a(4) = 253 since 4^4-253 = 3 and 4^4+253 = 509 are both prime. %o A075469 (PARI) a(n)=my(N=n^n); forprime(p=2,N, if(isprime(2*N-p), return(N-p))); -1 \\ _Charles R Greathouse IV_, Mar 16 2016 %Y A075469 Cf. A075468. %Y A075469 Cf. A000312, A047949. %K A075469 nonn %O A075469 2,2 %A A075469 _Lior Manor_, Sep 18 2002