OFFSET
0,3
COMMENTS
Diagonal sums of A106476.
FORMULA
a(n) = Sum{k=0..floor(n/2)} phi(n-2k+1).
MATHEMATICA
a[n_] := Sum[EulerPhi[n - 2*k + 1], {k, 0, Floor[n/2]}]; Array[a, 60, 0] (* Amiram Eldar, Nov 16 2024 *)
CROSSREFS
KEYWORD
easy,nonn,changed
AUTHOR
Paul Barry, May 03 2005
STATUS
approved