A353232 - cp's OEIS frontend

A353232 a(n) is the number of ways to split [n] = {1,2,...,n} into two (possibly empty) complementary intervals {1,2,...,i} and {i+1,i+2,...,n} and then, if both intervals are nonempty, select 2 nonempty blocks/cells (i.e., subintervals) from each of them, or if one of the intervals is empty, select 2 nonempty blocks/cells from the nonempty interval.

n	a(n)
1	0
2	2
3	6
4	13
5	26
6	51
7	98
8	182
9	324
10	552
11	902
12	1419
13	2158
14	3185
15	4578
16	6428
17	8840
18	11934
19	15846
20	20729
21	26754
22	34111
23	43010
24	53682
25	66380
26	81380
27	98982
28	119511
29	143318
30	170781
31	202306
32	238328
33	279312
34	325754
35	378182
36	437157
37	503274
38	577163
39	659490
40	750958

[0, 2, 6, 13, 26, 51, 98, 182, 324, 552, 902, 1419, 2158, 3185, 4578, 6428, 8840, 11934, 15846, 20729, 26754, 34111, 43010, 53682, 66380, 81380, 98982, 119511, 143318, 170781, 202306, 238328, 279312, 325754, 378182, 437157, 503274, 577163, 659490, 750958]

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