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 A106477 #7 Nov 16 2024 02:58:01
%S A106477 1,1,3,3,7,5,13,9,19,13,29,17,41,23,49,31,65,37,83,45,95,55,117,63,
%T A106477 137,75,155,87,183,95,213,111,233,127,257,139,293,157,317,173,357,185,
%U A106477 399,205,423,227,469,243,511,263,543,287,595,305,635,329,671,357,729,373
%N A106477 Diagonal sums of Euler phi function sequence array.
%C A106477 Diagonal sums of A106476.
%F A106477 a(n) = Sum{k=0..floor(n/2)} phi(n-2k+1).
%t A106477 a[n_] := Sum[EulerPhi[n - 2*k + 1], {k, 0, Floor[n/2]}]; Array[a, 60, 0] (* _Amiram Eldar_, Nov 16 2024 *)
%Y A106477 Cf. A000010, A106476, A106478, A106479, A106480.
%K A106477 easy,nonn
%O A106477 0,3
%A A106477 _Paul Barry_, May 03 2005