A106477 - OEIS

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A106477

Diagonal sums of Euler phi function sequence array.

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

COMMENTS

Diagonal sums of A106476.

LINKS

Table of n, a(n) for n=0..59.

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