A275027 - cp's OEIS frontend

A275027 a(n) = Sum_{k=0..n} C(n,k)^2C(n-k,k), where C(n,k) denotes the binomial coefficient n!/(k!(n-k)!).

n	a(n)
0	1
1	1
2	5
3	19
4	85
5	401
6	1931
7	9605
8	48469
9	248365
10	1286605
11	6726875
12	35441275
13	187935775
14	1002122525
15	5369287019
16	28889315669
17	156015203845
18	845330354321
19	4593724615175
20	25029614166685
21	136704935601785
22	748273234994675
23	4103928115592365
24	22549175326327675
25	124105065258631651
26	684100888645922051
27	3776354280849020005

[1, 1, 5, 19, 85, 401, 1931, 9605, 48469, 248365, 1286605, 6726875, 35441275, 187935775, 1002122525, 5369287019, 28889315669, 156015203845, 845330354321, 4593724615175, 25029614166685, 136704935601785, 748273234994675, 4103928115592365, 22549175326327675, 124105065258631651, 684100888645922051, 3776354280849020005]

cp's OEIS Frontend

A275027 a(n) = Sum_{k=0..n} C(n,k)^2C(n-k,k), where C(n,k) denotes the binomial coefficient n!/(k!(n-k)!).

Table of values

List of values

cp's OEIS Frontend

A275027 a(n) = Sum_{k=0..n} C(n,k)^2*C(n-k,k), where C(n,k) denotes the binomial coefficient n!/(k!*(n-k)!).

Table of values

List of values

A275027 a(n) = Sum_{k=0..n} C(n,k)^2C(n-k,k), where C(n,k) denotes the binomial coefficient n!/(k!(n-k)!).