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 A280577 #9 Jan 05 2017 21:05:43
%S A280577 1,2,3,4,6,5,9,8,10,9,15,10,18,13,15,16,24,15,27,18,22,21,33,20,32,25,
%T A280577 31,26,42,23,45,32,36,33,41,30,54,37,43,36,60,33,63,42,46,45,69,40,66,
%U A280577 45,57,50,78,45,67,52,64,57,87,46,90,61,67,64,80,53,99,66,78
%N A280577 a(n) = eulerphi(n) + floor(n/2).
%F A280577 a(n) = A000010(n) + A004526(n).
%F A280577 G.f.: x^2/((1 + x)*(1 - x)^2) + Sum_{k>=1} mu(k)*x^k/(1 - x^k)^2. - _Ilya Gutkovskiy_, Jan 05 2017
%p A280577 with(numtheory): A280577:=n->phi(n)+floor(n/2): seq(A280577(n), n=1..100); # _Wesley Ivan Hurt_, Jan 05 2017
%t A280577 Table[EulerPhi[n] + Floor[n/2], {n, 100}] (* _Wesley Ivan Hurt_, Jan 05 2017 *)
%o A280577 (PARI) a(n) = eulerphi(n) + floor(n/2);
%Y A280577 Cf. A000010, A004526.
%Y A280577 Cf. A097026, A097027, A097028, A097029.
%K A280577 nonn,easy
%O A280577 1,2
%A A280577 _Michel Marcus_, Jan 05 2017