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.

A227260 Number of nX3 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X4 binary array having a sum of two or less, with rows and columns of the latter in lexicographically nondecreasing order.

Table of values

n a(n)
1 4
2 23
3 98
4 353
5 1111
6 3136
7 8065
8 19146
9 42385
10 88282
11 174361
12 328741
13 595043
14 1038979
15 1757024
16 2887631
17 4625512
18 7239575
19 11095178
20 16681436
21 24644396
22 35826978
23 51316667
24 72502032
25 101139243
26 139429856
27 190111239
28 256561119

List of values

[4, 23, 98, 353, 1111, 3136, 8065, 19146, 42385, 88282, 174361, 328741, 595043, 1038979, 1757024, 2887631, 4625512, 7239575, 11095178, 16681436, 24644396, 35826978, 51316667, 72502032, 101139243, 139429856, 190111239, 256561119]

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

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