A260185 - cp's OEIS frontend

A260185 a(n) is the number of ways to select an ordered pair of subsets of {2,...,n} such that each pair of elements from different subsets are relatively prime.

n	a(n)
1	1
2	3
3	9
4	21
5	63
6	111
7	333
8	693
9	1521
10	2577
11	7731
12	13491
13	40473
14	67833
15	119241
16	239481
17	718443
18	1340523
19	4021569
20	7494849
21	13356657
22	22271409
23	66814227
24	130266387
25	268286823
26	447212583
27	896472063
28	1684872063
29	5054616189
30	9566769789
31	28700309367
32	57402497367

[1, 3, 9, 21, 63, 111, 333, 693, 1521, 2577, 7731, 13491, 40473, 67833, 119241, 239481, 718443, 1340523, 4021569, 7494849, 13356657, 22271409, 66814227, 130266387, 268286823, 447212583, 896472063, 1684872063, 5054616189, 9566769789, 28700309367, 57402497367]

cp's OEIS Frontend

A260185 a(n) is the number of ways to select an ordered pair of subsets of {2,...,n} such that each pair of elements from different subsets are relatively prime.

Table of values

List of values