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 A158947 #15 Nov 21 2022 08:47:53
%S A158947 1,4,21,598,1555,497652,299593,320361028,1178277701,357046721884,
%T A158947 67546215517,19351522090518670,61054982558011,1502551437369035044,
%U A158947 33657152197069739919,45463945109198918808616,128583032925805678351
%N A158947 Inverse Euler transform of A156217.
%H A158947 Seiichi Manyama, <a href="/A158947/b158947.txt">Table of n, a(n) for n = 1..335</a>
%H A158947 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%F A158947 a(n) = (1/n)*Sum_{d|n} sigma(d)^d*moebius(n/d).
%p A158947 A158947 := proc(n) add(numtheory[sigma](d)^d*numtheory[mobius](n/d),d=numtheory[divisors](n))/n ; end: seq( A158947(n),n=1..40) ; # _R. J. Mathar_, Apr 02 2009
%p A158947 # The function EulerInvTransform is defined in A358451.
%p A158947 a := EulerInvTransform(A156217):
%p A158947 seq(a(n), n = 1..17); # _Peter Luschny_, Nov 21 2022
%t A158947 f[n_] := Block[{d = Divisors@n}, Plus @@ (DivisorSigma[1, d]^d*MoebiusMu[n/d])/n]; Array[f, 17] (* _Robert G. Wilson v_, May 04 2009 *)
%Y A158947 Cf. A008683, A156217, A217872.
%K A158947 easy,nonn
%O A158947 1,2
%A A158947 _Vladeta Jovovic_, Mar 31 2009
%E A158947 Extended by _R. J. Mathar_, Apr 02 2009