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 A092404 #16 Apr 17 2023 06:19:06
%S A092404 2,3,4,6,6,8,10,10,10,14,14,16,18,14,16,24,22,24,26,20,22,32,30,28,32,
%T A092404 30,30,40,36,38,46,36,36,40,36,48,54,42,40,56,52,54,62,44,46,68,62,58,
%U A092404 62,52,56,76,70,58,64,60,64,86,74,76
%N A092404 a(n) = phi(n) + phi(n+1).
%C A092404 A054521 is the following array A read along antidiagonals:
%C A092404 1, 0, 0, 0, 0, 0, ...
%C A092404 1, 1, 1, 1, 1, 1, ...
%C A092404 1, 0, 1, 0, 1, 0, ...
%C A092404 1, 1, 0, 1, 1, 0, ...
%C A092404 1, 0, 1, 0, 1, 0, ...
%C A092404 1, 1, 1, 1, 0, 1, ...
%C A092404 and a(n) is apparently the hook sum Sum_{k=0..n} A(n,k) + Sum_{r=0..n-1} A(r,n). - _R. J. Mathar_, Jun 30 2013
%H A092404 Vincenzo Librandi, <a href="/A092404/b092404.txt">Table of n, a(n) for n = 1..1000</a>
%t A092404 Table[(EulerPhi[n] + EulerPhi[n + 1]), {n, 60}] (* _Vincenzo Librandi_, Sep 27 2013 *)
%t A092404 Total/@Partition[EulerPhi[Range[70]],2,1] (* _Harvey P. Dale_, Dec 30 2015 *)
%o A092404 (PARI) for(i=1,60,print1(","eulerphi(i)+eulerphi(i+1)))
%Y A092404 Cf. A000010, A054521.
%K A092404 nonn,easy
%O A092404 1,1
%A A092404 _Jon Perry_, Mar 22 2004