OFFSET
1,3
LINKS
Iain Fox, Table of n, a(n) for n = 1..300
MATHEMATICA
f[n_] := Det[ Table[ If[i == j, 0, DivisorSigma[0, Abs[i - j]]], {i, 1, n}, {j, 1, n}]]; Table[Abs[f[n]], {n, 1, 21}]
PROG
(PARI) a(n) = matdet(matrix(n, n, i, j, if(i == j, 0, numdiv(abs(i-j))))) \\ Iain Fox, Feb 15 2018
CROSSREFS
KEYWORD
sign
AUTHOR
Robert G. Wilson v, May 26 2002
EXTENSIONS
a(22)-a(25) from Iain Fox, Feb 15 2018
STATUS
approved