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 A330148 #10 Sep 08 2022 08:46:24
%S A330148 1,3,11,30,94,238,692,1596,4536,9350,27840,52884,149668,294838,782432,
%T A330148 1463224,4095792,7460274,20229356,36847380,100317284,170262974,
%U A330148 492659240,814679680,2184447760,3965791284,9988168320,17883230712,49362800340,80674575956,213420581248
%N A330148 a(n) = Sum_{k=1..n} binomial(n,k) * phi(k) * phi(n - k + 1), where phi = A000010.
%F A330148 E.g.f.: (1/2) * d/dx (Sum_{k>=1} phi(k) * x^k / k!)^2.
%t A330148 Table[Sum[Binomial[n, k] EulerPhi[k] EulerPhi[n - k + 1], {k, 1, n}], {n, 1, 31}]
%t A330148 nmax = 31; CoefficientList[Series[(1/2) D[Sum[EulerPhi[k] x^k/k!, {k, 1, nmax}]^2, x], {x, 0, nmax}], x] Range[0, nmax]! // Rest
%o A330148 (Magma) [&+[Binomial(n,k)*EulerPhi(k)*EulerPhi(n-k+1):k in [1..n]]:n in [1..30]]; // _Marius A. Burtea_, Dec 03 2019
%o A330148 (PARI) a(n) = sum(k=1, n, binomial(n,k)*eulerphi(k)*eulerphi(n-k+1)); \\ _Michel Marcus_, Dec 03 2019
%Y A330148 Cf. A000010, A007318, A065093, A306988.
%K A330148 nonn
%O A330148 1,2
%A A330148 _Ilya Gutkovskiy_, Dec 03 2019