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 A163371 #14 Jun 02 2025 01:48:19 %S A163371 1,2,2,4,2,3,3,4,6,4,3,6,4,4,4,8,4,8,4,6,5,6,4,5,8,6,5,8,4,8,5,9,5,6, %T A163371 5,12,6,5,8,8,6,6,6,8,8,8,5,12,9,12,8,8,6,6,8,6,6,8,5,10,8,6,10,12,8, %U A163371 10,6,9,6,10,8,12,9,9,12,10,6,10,6,12,8,9,8,12,9,8 %N A163371 a(n) = tau(phi(sigma(n))). %H A163371 G. C. Greubel, <a href="/A163371/b163371.txt">Table of n, a(n) for n = 1..1000</a> %F A163371 a(n) = A000005(A000010(A000203(n))) = A000005(A062401(n)) = A062821(A000203(n)). %p A163371 with(numtheory): A163371:=n->tau(phi(sigma(n))): seq(A163371(n), n=1..150); # _Wesley Ivan Hurt_, Dec 19 2016 %t A163371 DivisorSigma[0, EulerPhi[DivisorSigma[1, Range[100]]]] (* _G. C. Greubel_, Dec 19 2016 *) %o A163371 (PARI) vector(50, n, numdiv(eulerphi(sigma(n)))) \\ _G. C. Greubel_, Dec 19 2016 %Y A163371 Cf. A000005, A000010, A000203, A062401, A062821. %K A163371 nonn,easy %O A163371 1,2 %A A163371 _Jaroslav Krizek_, Jul 25 2009