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.

A099581 a(n) = Sum_{k=0..floor(n/2)} binomial(n-k,k-1)*3^(n-k-1).

Table of values

n a(n)
0 0
1 0
2 1
3 3
4 15
5 54
6 216
7 810
8 3105
9 11745
10 44631
11 169128
12 641520
13 2431944
14 9221121
15 34959195
16 132543135
17 502506990
18 1905156936
19 7222991778
20 27384465825
21 103822372809
22 393620574951
23 1492328843280
24 5657848431840
25 21450531825360

List of values

[0, 0, 1, 3, 15, 54, 216, 810, 3105, 11745, 44631, 169128, 641520, 2431944, 9221121, 34959195, 132543135, 502506990, 1905156936, 7222991778, 27384465825, 103822372809, 393620574951, 1492328843280, 5657848431840, 21450531825360]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.