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 A063473 #17 Apr 13 2024 14:55:37
%S A063473 1,-1,-2,-2,-2,-2,-3,-1,-2,-3,-2,-2,-2,-1,-2,-4,-3,-1,-2,0,-1,-3,-3,
%T A063473 -3,-3,-2,-3,-2,-1,-1,-2,-1,0,-2,-1,-3,-4,-3,-2,-4,-4,-4,-3,-1,-2,-1,
%U A063473 0,2,1,1,0,-2,-3,-3,-4,-4,-5,-5,-5,-3,-3,-1,-1,-2,-1,-3,-2,-1,-2,-4,-3,-1,0,1,0,-1,-1,-1,-2,0,1,0,-1,-1,-1,-2,-3,-4,-3
%N A063473 a(n) = M(2*n-1), where M(n) is Mertens's function (A002321): Sum_{k=1..n} mu(k), where mu = Moebius function (A008683).
%H A063473 Harry J. Smith, <a href="/A063473/b063473.txt">Table of n, a(n) for n = 1..1000</a>
%o A063473 (PARI) M(n)=sum(k=1,n,moebius(k));
%o A063473 j=[]; for(n=1,200,j=concat(j,M(2*n-1))); j
%o A063473 (PARI) { for (n=1, 1000, if (n>1, a+=moebius(2*n - 2) + moebius(2*n - 1), a=1); write("b063473.txt", n, " ", a) ) } \\ _Harry J. Smith_, Aug 22 2009
%Y A063473 Cf. A002321, A008683.
%K A063473 easy,sign
%O A063473 1,3
%A A063473 _Jason Earls_, Jul 27 2001