A260897 Numerator of det(M) where M is the n X n matrix with M[i,j] = 1/lcm(i,j).

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 8, 2, 16, 16, 32, 8, 64, 32, 64, 4, 8, 8, 256, 128, 512, 256, 2048, 256, 1024, 1024, 2048, 2048, 8192, 4096, 16384, 128, 2048, 2048, 4096, 8192, 32768, 65536, 131072, 16384, 131072

Offset: 1

Author

Robert G. Wilson v, Aug 03 2015

Keywords

• nonn

Comments

All terms are powers of two (A000079).

Links

• Robert G. Wilson v, Table of n, a(n) for n = 1..500

Crossrefs

Cf. A060841, A260502.

Programs

Maple

seq(denom(1/LinearAlgebra:-Determinant(Matrix(n,n,1/ilcm))),n=1..100); # Robert Israel, Aug 17 2015

Mathematica

f[n_] := Denominator[1 / Det[ Table[ 1/LCM[i, j], {i, n}, {j, n}]]]; Array[f, 73]

PARI

vector(80, n, denominator(1/matdet(matrix(n, n, i, j, 1/lcm(i, j))))) \\ Michel Marcus, Aug 04 2015

Formula

a(n) = 2^A260502(n).