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 A163378 #9 Dec 20 2016 19:41:57 %S A163378 1,1,1,3,1,3,1,3,3,3,1,3,1,3,3,7,1,3,1,3,3,3,1,7,3,3,3,3,1,7,1,3,3,3, %T A163378 3,12,1,3,3,7,1,7,1,3,3,3,1,7,3,3,3,3,1,7,3,7,3,3,1,7,1,3,3,12,3,7,1, %U A163378 3,3,7,1,7,1,3,3,3,3,7,1,7,7,3,1,7,3,3 %N A163378 a(n) = sigma(phi(tau(n))). %H A163378 G. C. Greubel, <a href="/A163378/b163378.txt">Table of n, a(n) for n = 1..1000</a> %F A163378 a(n) = A000203(A000010(A000005(n))) = A000203(A163109(n)) = A062402(A000005(n)). %t A163378 Table[DivisorSigma[1,EulerPhi[DivisorSigma[0,n]]],{n,100}] (* _Harvey P. Dale_, Jun 21 2016 *) %o A163378 (PARI) vector(100, n, sigma(eulerphi(numdiv(n)))) \\ _G. C. Greubel_, Dec 20 2016 %Y A163378 Cf. A000005, A000010, A000203, A062402, A163109. %K A163378 nonn %O A163378 1,4 %A A163378 _Jaroslav Krizek_, Jul 25 2009 %E A163378 More terms from _Harvey P. Dale_, Jun 21 2016