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.

A156430 Number of n X n arrays of squares of integers, symmetric about both diagonal and antidiagonal, with all rows summing to 2.

Table of values

n a(n)
2 1
3 2
4 10
5 12
6 84
7 132
8 954
9 1728
10 13290
11 26820
12 217500
13 481320
14 4086600
15 9783480
16 86549820
17 221921280
18 2037627900
19 5552479800
20 52745205240
21 151802154000
22 1487961422640
23 4500041903280
24 45412066438200
25 143712079822080
26 1490217165997560
27 4917227802767280

List of values

[1, 2, 10, 12, 84, 132, 954, 1728, 13290, 26820, 217500, 481320, 4086600, 9783480, 86549820, 221921280, 2037627900, 5552479800, 52745205240, 151802154000, 1487961422640, 4500041903280, 45412066438200, 143712079822080, 1490217165997560, 4917227802767280]

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

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