OFFSET
1,6
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000
N. J. A. Sloane, Transforms
MAPLE
with(numtheory): a:= proc(n) option remember; local d, j; if n=1 then -1 else (add(d*a(d), d=divisors(n-1)) +add(add(d*a(d), d=divisors(j)) *a(n-j), j=1..n-2))/(n-1) fi end: seq(a(n), n=1..40); # Alois P. Heinz, Sep 06 2008
MATHEMATICA
a[n_] := a[n] = If[n == 1, -1, (Sum[d a[d], {d, Divisors[n-1]}] + Sum[Sum[d a[d], {d, Divisors[j]}] a[n-j], {j, 1, n-2}])/(n-1)];
Array[a, 40] (* Jean-François Alcover, Nov 08 2020, after Alois P. Heinz *)
CROSSREFS
KEYWORD
sign,eigen
AUTHOR
Christian G. Bower, Jan 04 1999
STATUS
approved