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.

A177555 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up.

Table of values

n a(n)
0 1
1 1
2 6
3 67
4 1345
5 42540
6 1954681
7 123179785
8 10202958366
9 1075213876195
10 140503060278001
11 22298495343474372
12 4224949686497139601
13 942067522308032112721
14 244201603555824428994486
15 72820161285112813781838787
16 24752401241200431437146873345

List of values

[1, 1, 6, 67, 1345, 42540, 1954681, 123179785, 10202958366, 1075213876195, 140503060278001, 22298495343474372, 4224949686497139601, 942067522308032112721, 244201603555824428994486, 72820161285112813781838787, 24752401241200431437146873345]

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

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