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 A248003 #32 Jul 13 2024 13:48:06
%S A248003 1,1,3,4,10,3,21,16,27,10,55,12,78,21,30,64,136,27,171,40,63,55,253,
%T A248003 48,250,78,243,84,406,30,465,256,165,136,210,108,666,171,234,160,820,
%U A248003 63,903,220,270,253,1081,192,1029,250,408,312,1378,243,550,336
%N A248003 a(n) = (sum of totatives of n ) / (2^(omega(n)-1)); a(n) = A023896(n) / A007875(n).
%H A248003 G. C. Greubel, <a href="/A248003/b248003.txt">Table of n, a(n) for n = 1..5000</a>
%F A248003 a(n) = A023896(n)/A007875(n) = A023896(n)/2^(A001221(n)-1).
%F A248003 a(n) = (n/2)*A000010(n)/2^(A001221(n)-1) = n*A023022(n)/A007875(n).
%F A248003 a(n) = 2*A023896(n)/A034444(n) = n*A000010(n)/A034444(n).
%F A248003 a(n) is multiplicative with a(p^e) = (p-1)*p^(2e-1)/2.
%F A248003 Sum_{k>=1} 1/a(k) = Product_{primes p} (1 + 2*p/((p-1)^2 * (p+1))) = 3.96555686901754604330173765246769123681199917183404752314230450571038281... - _Vaclav Kotesovec_, Sep 20 2020
%e A248003 For n=30; a(30) = A023896(30)/A007875(30) = 120/4 = 30.
%t A248003 Table[n*EulerPhi[n]/2^PrimeNu[n], {n,60}] (* _G. C. Greubel_, May 22 2017 *)
%o A248003 (Magma) [(n*EulerPhi(n)/2)/(2^((#(PrimeDivisors(n)))-1)): n in [1..100]]
%o A248003 (PARI) A248003(n) = n*eulerphi(n)/2^omega(n); \\ _G. C. Greubel_, May 22 2017; Jul 13 2024
%o A248003 (SageMath)
%o A248003 def A248003(n): return int(n*euler_phi(n)/2^(gp.omega(n)))
%o A248003 [A248003(n) for n in range(1,61)] # _G. C. Greubel_, Jul 13 2024
%Y A248003 Cf. A000010, A001221, A007875, A023022, A023896, A034444.
%K A248003 nonn,mult
%O A248003 1,3
%A A248003 _Jaroslav Krizek_, Sep 29 2014