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 A130088 #13 Feb 12 2019 01:18:38
%S A130088 1,2,3,2,5,3,7,1,3,25,22,21,104,21,20,11,408,585,380,55,6272,2431,
%T A130088 14904,95,176000,25857,1008,149891,356352,10625,510136,35397,7904,
%U A130088 224315,35280,776457,118513664,8265,135200,5425,143972204544,108150889
%N A130088 a(n) = numerator of Product_{k=1..n} k^mu(n+1-k), where mu(k) = A008683(k).
%e A130088 a(5) = numerator(1^(-1)*2^(0)*3^(-1)*4^(-1)*5^(1)) = numerator(5/12) = 5.
%p A130088 with(numtheory): a:=n->numer(mul(k^mobius(n+1-k),k=1..n)): seq(a(n),n=1..50); # _Emeric Deutsch_, May 09 2007
%o A130088 (PARI) a(n) = numerator(prod(k=1, n, k^moebius(n+1-k))); \\ _Michel Marcus_, Feb 12 2019
%Y A130088 Cf. A130086, A130087, A130089.
%K A130088 frac,nonn
%O A130088 1,2
%A A130088 _Leroy Quet_, May 06 2007
%E A130088 More terms from _Emeric Deutsch_, May 09 2007