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.

A289313 The number of upper-triangular matrices with integer entries whose absolute sum is equal to n and such that each row contains a nonzero entry.

Table of values

n a(n)
0 1
1 2
2 10
3 74
4 722
5 8786
6 128218
7 2182554
8 42456226
9 929093538
10 22590839466
11 604225121258
12 17630145814898
13 557285515817970
14 18970857530674554
15 691929648113663802
16 26919562120779248962
17 1112769248605003393858
18 48704349211392743606602

List of values

[1, 2, 10, 74, 722, 8786, 128218, 2182554, 42456226, 929093538, 22590839466, 604225121258, 17630145814898, 557285515817970, 18970857530674554, 691929648113663802, 26919562120779248962, 1112769248605003393858, 48704349211392743606602]

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

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