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 A078580 #8 Nov 03 2019 06:47:07 %S A078580 0,1,0,0,-1,-1,0,0,-1,0,-1,0,0,0,0,0,0,0,-1,0,0,0,0,1,0,1,0,-1,-1,0,0, %T A078580 -1,0,1,0,0,0,0,0,0,0,1,0,1,1,0,0,0,1,0,0,0,0,-1,1,0,0,-1,0,0,0,0,-1, %U A078580 0,0,1,0,-1,0,-1,0,-1,0,0,-1,0,0,-1,0,-1,0,0,0,0,0,0,0,0,0,0,1,-1,0,0,0,-1,0,0,0,0,0 %N A078580 Moebius function mu of the average of n-th twin prime pair. %H A078580 Amiram Eldar, <a href="/A078580/b078580.txt">Table of n, a(n) for n = 1..10000</a> %F A078580 a(n) = A008683(A014574(n)). %t A078580 midQ[n_] := PrimeQ[n-1] && PrimeQ[n+1]; MoebiusMu[Select[Range[4000], midQ]] (* _Amiram Eldar_, Nov 03 2019 *) %Y A078580 Cf. A008683, A014574, A078579. %K A078580 sign %O A078580 1,1 %A A078580 _Reinhard Zumkeller_, Nov 29 2002