cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A219692 a(n) = Sum_{j=0..floor(n/3)} (-1)^j C(n,j) * C(2j,j) * C(2n-2j,n-j) * (C(2n-3j-1,n) + C(2n-3j,n)).

Table of values

n a(n)
0 2
1 6
2 54
3 564
4 6390
5 76356
6 948276
7 12132504
8 158984694
9 2124923460
10 28877309604
11 398046897144
12 5554209125556
13 78328566695736
14 1114923122685720
15 15999482238880464
16 231253045986317814
17 3363838379489630916

List of values

[2, 6, 54, 564, 6390, 76356, 948276, 12132504, 158984694, 2124923460, 28877309604, 398046897144, 5554209125556, 78328566695736, 1114923122685720, 15999482238880464, 231253045986317814, 3363838379489630916]