OFFSET
1,2
COMMENTS
For prime p, a(p) = 2^(p-2)*p. - Jon E. Schoenfield, Feb 03 2018
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000
MAPLE
with(numtheory):
a:= proc(n) option remember; `if`(n=1, 1, n*2^(n-2)-
add(a(d)*a(n/d), d=divisors(n) minus {1, n})/2)
end:
seq(a(n), n=1..35); # Alois P. Heinz, Mar 07 2018
MATHEMATICA
nn=50;
sys=Table[2^(n-1)*n==Sum[a[d]*a[n/d], {d, Divisors[n]}], {n, nn}];
Array[a, nn]/.Solve[sys, Array[a, nn]][[2]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Feb 03 2018
STATUS
approved