A075691 Let M(k) be the k X k matrix m_(i,j) = i (mod j) - j (mod i); then a(n) = det(M(2*n)).

1, 1, 1, 81, 81, 53361, 57744801, 119836809, 3231369355201, 3030985307728225, 1788629609520903241, 6271587203171610961, 566023524795406585035241, 135075661787247287434787209, 202466242679530681259970248569, 153329310994334874643836218452225

Offset

0,4

Comments

Terms are squares. det(M(2*n+1))=0.

Links

Robert Israel, Table of n, a(n) for n = 0..224

Maple

f:= proc(n) LinearAlgebra:-Determinant(Matrix(2*n, 2*n, (i, j) -> (i mod j) - (j mod i))) end proc:
map(f, [$0..20]); # Robert Israel, Dec 01 2020

Mathematica

a[0] = 1;
a[n_] := Det@Array[Mod[#1, #2] - Mod[#2, #1]&, {2n, 2n}];
Table[a[n], {n, 0, 15}] (* Jean-François Alcover, May 17 2023 *)

Prog

(PARI) a(n)=matdet(matrix(2*n, 2*n, i, j, i%j-j%i))

Crossrefs

Sequence in context: A206143 A087410 A177842 * A055390 A186472 A183984

Adjacent sequences: A075688 A075689 A075690 * A075692 A075693 A075694

Keyword

nonn

Author

Benoit Cloitre, Oct 12 2002

Status

approved