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A106477
Diagonal sums of Euler phi function sequence array.
3
1, 1, 3, 3, 7, 5, 13, 9, 19, 13, 29, 17, 41, 23, 49, 31, 65, 37, 83, 45, 95, 55, 117, 63, 137, 75, 155, 87, 183, 95, 213, 111, 233, 127, 257, 139, 293, 157, 317, 173, 357, 185, 399, 205, 423, 227, 469, 243, 511, 263, 543, 287, 595, 305, 635, 329, 671, 357, 729, 373
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