A019021 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A019021 as a simple table

n	a(n)
2	3
3	7
4	30
5	140
6	908
7	5586
8	35137
9	226799
10	1489781
11	9920319
12	67048694
13	458884910
14	3172523046
15	22127603235
16	155529572271

[3,7,30,140,908,5586,35137,226799,1489781,9920319, 67048694,458884910,3172523046,22127603235, 155529572271]