A215972 - OEIS

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A215972 as a simple table

n	a(n)
1	1
2	3
3	6
4	13
5	15
6	26
7	30
8	55
9	61
10	63
11	3446
12	108996
13	3625183
14	13951973
15	28010902
16	7165572248
17	14335792540
18	114636743487
19	229264368710
20	458534096495

[1,3,6,13,15,26,30,55,61,63,3446,108996,3625183, 13951973,28010902,7165572248,14335792540, 114636743487,229264368710,458534096495]