The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A344577

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A344577

a(n) = Sum_{d|n, d<n} phi(n-d) for n >= 2.
(history; published version)

#5 by Wesley Ivan Hurt at Sun May 23 21:43:27 EDT 2021

STATUS

editing

approved

#4 by Wesley Ivan Hurt at Sun May 23 21:41:51 EDT 2021

COMMENTS

If p is prime, a(p) = phi(n-1).

#3 by Wesley Ivan Hurt at Sun May 23 21:36:39 EDT 2021

NAME

a(n) = Sum_{d|n, d<n} phi(n-d) for n >= 2.

DATA

0, 1, 1, 3, 2, 8, 2, 10, 6, 14, 4, 26, 4, 22, 14, 22, 8, 42, 6, 44, 20, 30, 10, 70, 16, 40, 26, 56, 12, 102, 8, 66, 34, 52, 36, 116, 12, 66, 42, 110, 16, 140, 12, 100, 68, 66, 22, 176, 28, 118, 52, 104, 24, 178, 58, 164, 60, 88, 28, 288, 16, 106, 100, 138, 72, 212, 20, 166, 74

OFFSET

1,4

2,3

#2 by Wesley Ivan Hurt at Sun May 23 21:33:23 EDT 2021

NAME

allocated for Wesley Ivan Hurt

a(n) = Sum_{d|n, d<n} phi(n-d).

DATA

OFFSET

1,4

EXAMPLE

a(10) = Sum_{d|10, d<10} phi(10-d) = phi(10-1) + phi(10-2) + phi(10-5) = 6 + 4 + 4 = 14.

MATHEMATICA

Table[Sum[EulerPhi[n - k] (1 - Ceiling[n/k] + Floor[n/k]), {k, n - 1}], {n, 100}]

CROSSREFS

Cf. A000010 (phi).

KEYWORD

allocated

nonn

AUTHOR

Wesley Ivan Hurt, May 23 2021

STATUS

approved

editing

#1 by Wesley Ivan Hurt at Sun May 23 21:33:23 EDT 2021

NAME

allocated for Wesley Ivan Hurt

KEYWORD

allocated

STATUS

approved