A071547 - OEIS

A071547

Determinant of the n X n matrix whose element (i,j) equals f(|i-j|) where f(n) is the sum of middle divisors (A071090).

0, -1, 2, 0, -2, 3, 8, -259, -9006, 37575, 1988916, 41615129, -444915500, 4752358604, -50506657344, 532544416084, -4450492081868, -10234691885873, 241215169689690, 21696729746925312, 123619114295636184, 174381272189413488, -43909101832286346168, -439142701170244441024

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..24.

MATHEMATICA

f[n_] := If[n > 0, Plus @@ Select[Divisors[n], Sqrt[n/2] <= # < Sqrt[n*2] &], 0]; Table[ Det[ Table[ f[ Abs[i - j]], {i, 1, n}, {j, 1, n}]], {n, 1, 25}]

CROSSREFS

Cf. A071090.

Sequence in context: A233399 A226432 A072514 * A220222 A089839 A206823

Adjacent sequences: A071544 A071545 A071546 * A071548 A071549 A071550

KEYWORD

sign

AUTHOR

Robert G. Wilson v, May 30 2002

STATUS

approved