OFFSET
0,4
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..200
EXAMPLE
a(6)=21 because A001006(6)=51, having as proper divisors 1, 3 and 17. - Emeric Deutsch, Dec 31 2008
MAPLE
with(numtheory): M := proc (n) options operator, arrow: sum(binomial(n, 2*k)*binomial(2*k, k)/(k+1), k = 0 .. n) end proc: seq(sigma(M(n))-M(n), n = 0 .. 30); # Emeric Deutsch, Dec 31 2008
MATHEMATICA
mot[0] = 1; mot[n_] := mot[n] = mot[n - 1] + Sum[mot[k] * mot[n - 2 - k], {k, 0, n - 2}]; propDivSum[n_] := DivisorSigma[1, n] - n; Table[propDivSum[mot[n]], {n, 0, 30}] (* Amiram Eldar, Nov 26 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Dec 20 2008
EXTENSIONS
Extended by Emeric Deutsch, Dec 31 2008
STATUS
approved