A228513 - cp's OEIS frontend

A228513 a(n) = Sum_{k=0..n} 2^k*(n!/k!)^2.

n	a(n)
0	1
1	3
2	16
3	152
4	2448
5	61232
6	2204416
7	108016512
8	6913057024
9	559957619456
10	55995761946624
11	6775487195543552
12	975670156158275584
13	164888256390748581888
14	32318098252586722066432
15	7271572106832012464979968
16	1861522459348995191034937344
17	537979990751859610209097023488

[1, 3, 16, 152, 2448, 61232, 2204416, 108016512, 6913057024, 559957619456, 55995761946624, 6775487195543552, 975670156158275584, 164888256390748581888, 32318098252586722066432, 7271572106832012464979968, 1861522459348995191034937344, 537979990751859610209097023488]

cp's OEIS Frontend

A228513 a(n) = Sum_{k=0..n} 2^k*(n!/k!)^2.

Table of values

List of values