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.

A203969 Number of n X 2 0..2 arrays with every 1 immediately preceded by 0 to the left or above, and every 2 immediately preceded by 0 1 to the left or above.

Table of values

n a(n)
1 2
2 7
3 29
4 106
5 396
6 1488
7 5569
8 20859
9 78133
10 292644
11 1096125
12 4105590
13 15377699
14 57598086
15 215736791
16 808054127
17 3026612006
18 11336343903
19 42460908170
20 159039700345
21 595692067467
22 2231197862121
23 8357076036219
24 31301894398172

List of values

[2, 7, 29, 106, 396, 1488, 5569, 20859, 78133, 292644, 1096125, 4105590, 15377699, 57598086, 215736791, 808054127, 3026612006, 11336343903, 42460908170, 159039700345, 595692067467, 2231197862121, 8357076036219, 31301894398172]

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

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