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 A130492 #12 Feb 09 2025 14:23:01
%S A130492 1,1,2,6,12,20,10,84,840,72,630,1320,2772,1560,90090,42,240240,1904,
%T A130492 46410,95760,639540,5040,9699690,637560,14316120,92400,176125950,
%U A130492 308880,20078358300,475020,33845175,7447440,116925953760,110880,501401225325,2227680,244906200
%N A130492 a(n) = denominator of Sum_{k=1..n} k^mu(n+1-k), where mu(m) = A008683(m).
%C A130492 Numerator of Sum_{k=1..n} k^mu(n+1-k) is A130491(n).
%p A130492 A130492 := proc(n) denom(add(k^numtheory[mobius](n+1-k),k=1..n)) ; end: seq(A130492(n),n=1..40) ; # _R. J. Mathar_, Oct 16 2007
%t A130492 Table[Denominator[Sum[k^MoebiusMu[n+1-k], {k, n}]], {n, 37}] (* _James C. McMahon_, Feb 09 2025 *)
%Y A130492 Cf. A130491, A080306, A080326.
%K A130492 frac,nonn
%O A130492 1,3
%A A130492 _Leroy Quet_, May 29 2007
%E A130492 More terms from _R. J. Mathar_, Oct 16 2007
%E A130492 a(36)-a(37) from _James C. McMahon_, Feb 09 2025