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 A270388 #16 Nov 17 2024 07:17:04 %S A270388 1,0,0,0,1,0,0,3,1,0,8,0,1,8,0,0,13,0,8,17,1,0,0,20,1,21,8,0,19,0,0,3, %T A270388 1,34,8,0,1,29,8,0,7,0,8,41,1,0,0,21,31,3,8,0,13,9,8,3,1,0,20,0,1,59, %U A270388 0,20,49,0,8,26,1,0,0,0,1,3,8,20,49,0,48,75,1,0,56,20,1,32,24,0,49,28,8,65,1,39,0,0,85,3,68,0 %N A270388 a(n) = A048739(n-2) mod n. %C A270388 If n is an odd prime, a(n) = 0. In other words, ((1-sqrt(2))^p + (1+sqrt(2))^p - 2) is divisible by p where p is an odd prime. %F A270388 a(n) = (((1-sqrt(2))^n + (1+sqrt(2))^n - 2) / 4) mod n, for n > 1. %o A270388 (PARI) a048379(n) = my(w=quadgen(8));-1/2+(3/4+1/2*w)*(1+w)^n+(3/4-1/2*w)*(1-w)^n; %o A270388 a(n) = a048379(n-2) % n; %Y A270388 Cf. A000129, A048739. %K A270388 nonn %O A270388 2,8 %A A270388 _Altug Alkan_, Mar 16 2016