OFFSET
1,1
COMMENTS
Shifts left and halves under Weigh transform.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..500
N. J. A. Sloane, Transforms
FORMULA
a(n) = 2 * A005753(n).
MAPLE
b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
add(binomial(a(i), j)*b(n-i*j, i-1), j=0..n/i)))
end:
a:= n-> `if`(n=1, 2, 2*b((n-1)$2)):
seq(a(n), n=1..40); # Alois P. Heinz, May 20 2013
MATHEMATICA
b[n_, i_] := b[n, i] = If[n==0, 1, If[i<1, 0, Sum[Binomial[a[i], j]*b[n - i*j, i-1], {j, 0, n/i}]]];
a[n_] := If[n==1, 2, 2*b[n-1, n-1]];
Table[a[n], {n, 1, 40}] (* Jean-François Alcover, Mar 01 2016, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn,eigen
AUTHOR
Christian G. Bower, Jan 04 1999
STATUS
approved