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 A344573 #7 May 15 2025 19:22:13
%S A344573 1,2,3,10,33,196,1153,9226,82947,829474,8294401,99533004,1194393601,
%T A344573 16721511554,250822656035,4013162505226,64210599936001,
%U A344573 1155790798931140,20804234379264001,416084687586109482,8737778439290881155,192231125664407654402,4229084764616785920001
%N A344573 a(n) = Sum_{d|n} phi(d!).
%C A344573 Inverse Möbius transform of phi(n!) (A048855). - _Wesley Ivan Hurt_, Mar 31 2025
%e A344573 a(6) = Sum_{d|6} phi(d!) = phi(1!) + phi(2!) + phi(3!) + phi(6!) = 1 + 1 + 2 + 192 = 196.
%t A344573 Table[Sum[EulerPhi[k!] (1 - Ceiling[n/k] + Floor[n/k]), {k, n}], {n, 30}]
%Y A344573 Cf. A000010 (phi), A048855.
%K A344573 nonn
%O A344573 1,2
%A A344573 _Wesley Ivan Hurt_, May 23 2021