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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.

A260908 Numerator of 1/det(M) where M is the n X n matrix with M[i,j] = 1/gcd(i,j).

Table of values

n a(n)
1 1
2 -2
3 3
4 -12
5 15
6 45
7 -105
8 420
9 -1890
10 -4725
11 10395
12 31185
13 -135135
14 -315315
15 -4729725
16 4729725
17 -80405325
18 -723647925
19 1527701175
20 7638505875
21 53469541125
22 117632990475
23 -245959889175
24 -737879667525
25 18446991688125
26 79936963981875
27 -2158298027510625

List of values

[1, -2, 3, -12, 15, 45, -105, 420, -1890, -4725, 10395, 31185, -135135, -315315, -4729725, 4729725, -80405325, -723647925, 1527701175, 7638505875, 53469541125, 117632990475, -245959889175, -737879667525, 18446991688125, 79936963981875, -2158298027510625]

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

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