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A152981
Sum of divisors of Motzkin number A001006(n).
3
1, 1, 3, 7, 13, 32, 72, 128, 360, 1008, 3836, 9408, 15512, 66960, 252720, 785148, 1137960, 3340800, 13072776, 42465024, 69530400, 238761600, 678562560, 2412043920, 5270534880, 10943277120, 44922182340, 117229255200, 209990825568, 623486730240, 1698651339840, 7019676332760, 18578092462280
OFFSET
0,3
LINKS
FORMULA
a(n) = sigma(A001006(n)) = A000203(A001006(n)).
MAPLE
A152981 := proc(n) numtheory[sigma](A001006(n)) ; end proc:
seq(A152981(n), n=0..40) ; # R. J. Mathar, Jul 08 2011
MATHEMATICA
mot[0] = 1; mot[n_] := mot[n] = mot[n - 1] + Sum[mot[k] * mot[n - 2 - k], {k, 0, n - 2}]; Table[DivisorSigma[1, mot[n]], {n, 0, 32}] (* Amiram Eldar, Nov 26 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Dec 20 2008
STATUS
approved