A058880 - cp's OEIS frontend

A058880 a(n) = (1/(2n)) * Sum_{d|n} phi(d) * 2^(2n/d) + (2^((n-4)/2), if n is even).

n	a(n)
3	12
4	36
5	104
6	352
7	1172
8	4119
9	14572
10	52492
11	190652
12	699266
13	2581112
14	9587602
15	35791472
16	134219859
17	505290272
18	1908881998
19	7233629132
20	27487817244
21	104715393912
22	399822505942
23	1529755308212
24	5864062368274
25	22517998136936

[12, 36, 104, 352, 1172, 4119, 14572, 52492, 190652, 699266, 2581112, 9587602, 35791472, 134219859, 505290272, 1908881998, 7233629132, 27487817244, 104715393912, 399822505942, 1529755308212, 5864062368274, 22517998136936]

cp's OEIS Frontend

A058880 a(n) = (1/(2n)) * Sum_{d|n} phi(d) * 2^(2n/d) + (2^((n-4)/2), if n is even).

Table of values

List of values