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 A163372 #18 Sep 08 2022 08:45:46 %S A163372 1,3,3,12,3,7,7,15,28,12,7,28,12,15,15,72,12,60,15,28,31,28,15,31,72, %T A163372 28,31,60,15,60,31,91,31,39,31,195,39,31,60,60,28,63,42,60,60,60,31, %U A163372 168,91,168,60,96,39,63,60,63,63,60,31,124,72,63,124,312,60,124 %N A163372 a(n) = sigma(phi(sigma(n))). %H A163372 G. C. Greubel, <a href="/A163372/b163372.txt">Table of n, a(n) for n = 1..1000</a> %F A163372 a(n) = A000203(A000010(A000203(n))) = A000203(A062401(n)) = A062402(A000203(n)). %p A163372 with(numtheory): A163372:=n->sigma(phi(sigma(n))): seq(A163372(n), n=1..100); # _Wesley Ivan Hurt_, Oct 06 2017 %t A163372 DivisorSigma[1, EulerPhi[DivisorSigma[1, Range[100]]]] (* _G. C. Greubel_, Dec 20 2016 *) %o A163372 (PARI) vector(80, n, sigma(eulerphi(sigma(n)))) \\ _Michel Marcus_, Jul 31 2015 %o A163372 (Magma) [SumOfDivisors(EulerPhi(SumOfDivisors(n))): n in [1..80]]; // _Vincenzo Librandi_, Dec 20 2016 %Y A163372 Cf. A000010, A000203, A062401, A062402. %K A163372 nonn %O A163372 1,2 %A A163372 _Jaroslav Krizek_, Jul 25 2009 %E A163372 More terms from _Michel Marcus_, Jul 31 2015