OFFSET
0,3
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..200
EXAMPLE
a(5)=4 because the Motzkin number M(5)=21 has 4 divisors: 1,3,7 and 21. - Emeric Deutsch, Jan 14 2009
MAPLE
with(numtheory): M := proc (n) options operator, arrow: (sum((-1)^j*binomial(n+1, j)*binomial(2*n-3*j, n), j = 0 .. floor((1/3)*n)))/(n+1) end proc: seq(tau(M(n)), n = 0 .. 82); # Emeric Deutsch, Jan 14 2009
MATHEMATICA
mot[0] = 1; mot[n_] := mot[n] = mot[n - 1] + Sum[mot[k] * mot[n - 2 - k], {k, 0, n - 2}]; Table[DivisorSigma[0, mot[n]], {n, 0, 50}] (* Amiram Eldar, Nov 26 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Dec 20 2008
EXTENSIONS
Extended by Emeric Deutsch, Jan 14 2009
STATUS
approved