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 A130491 #13 Feb 10 2025 10:15:01
%S A130491 1,3,9,35,91,179,117,1181,14113,1415,14839,35617,85271,53251,3503033,
%T A130491 1879,12165719,106753,2870239,6436711,46663061,402271,850810423,
%U A130491 60658043,1473361913,10236631,21081760033,39731443,2762347887557
%N A130491 a(n) = numerator of Sum_{k=1..n} k^mu(n+1-k), where mu(m) = A008683(m).
%C A130491 Denominator of Sum_{k=1..n} k^mu(n+1-k) is A130492(n).
%p A130491 A130491 := proc(n) numer(add(k^numtheory[mobius](n+1-k),k=1..n)) ; end: seq(A130491(n),n=1..40) ; # _R. J. Mathar_, Oct 16 2007
%t A130491 Table[Numerator[Sum[k^MoebiusMu[n+1-k],{k,n}]],{n,29}] (* _James C. McMahon_, Feb 09 2025 *)
%o A130491 (PARI) a(n) = numerator(sum(k=1, n, k^moebius(n+1-k))); \\ _Michel Marcus_, Feb 09 2025
%Y A130491 Cf. A130492, A080306, A080326.
%K A130491 frac,nonn
%O A130491 1,2
%A A130491 _Leroy Quet_, May 29 2007
%E A130491 More terms from _R. J. Mathar_, Oct 16 2007