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.

A123781 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 4 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.

Table of values

n a(n)
1 1
2 1
3 5
4 7
5 41
6 65
7 384
8 649
9 3853
10 6745
11 40209
12 72334
13 431188
14 791144
15 4717533
16 8787824
17 52396271
18 98784645

List of values

[1, 1, 5, 7, 41, 65, 384, 649, 3853, 6745, 40209, 72334, 431188, 791144, 4717533, 8787824, 52396271, 98784645]

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

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