A274868 - cp's OEIS frontend

A274868 Number of set partitions of [n] into exactly four blocks such that all odd elements are in blocks with an odd index and all even elements are in blocks with an even index.

n	a(n)
4	1
5	2
6	7
7	14
8	35
9	70
10	155
11	310
12	651
13	1302
14	2667
15	5334
16	10795
17	21590
18	43435
19	86870
20	174251
21	348502
22	698027
23	1396054
24	2794155
25	5588310
26	11180715
27	22361430
28	44731051
29	89462102
30	178940587
31	357881174
32	715795115
33	1431590230
34	2863245995
35	5726491990
36	11453115051

[1, 2, 7, 14, 35, 70, 155, 310, 651, 1302, 2667, 5334, 10795, 21590, 43435, 86870, 174251, 348502, 698027, 1396054, 2794155, 5588310, 11180715, 22361430, 44731051, 89462102, 178940587, 357881174, 715795115, 1431590230, 2863245995, 5726491990, 11453115051]

cp's OEIS Frontend

A274868 Number of set partitions of [n] into exactly four blocks such that all odd elements are in blocks with an odd index and all even elements are in blocks with an even index.

Table of values

List of values