A153787 Largest proper divisor of Motzkin number A001006(n).

1, 2, 3, 7, 17, 1, 19, 167, 1094, 2899, 1, 13945, 56817, 155286, 284489, 785593, 3268191, 9099642, 16950673, 47515853, 133587741, 376586805, 1064242599, 1291914643, 12834909238, 36503886401, 1944142787, 19152993059, 1144562017

Offset

2,2

Links

Amiram Eldar, Table of n, a(n) for n = 2..200

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(divisors(M(i))[tau(M(i))-1], i = 2 .. 32); # Emeric Deutsch, Jan 18 2009

Mathematica

mot[0] = 1; mot[n_] := mot[n] = mot[n - 1] + Sum[mot[k] * mot[n - 2 - k], {k, 0, n - 2}]; lpd[n_] := n / FactorInteger[n][[1, 1]]; Table[lpd[mot[n]], {n, 2, 30}] (* Amiram Eldar, Nov 26 2019 *)

Crossrefs

Cf. A001006, A032742, A152766, A152982.

Sequence in context: A034732 A000278 A270525 * A141795 A077322 A174359

Adjacent sequences: A153784 A153785 A153786 * A153788 A153789 A153790

Keyword

nonn

Author

Omar E. Pol, Jan 16 2009

Extensions

Extended by Emeric Deutsch, Jan 18 2009

a(23)-a(27) and a(29)-a(30) corrected by Amiram Eldar, Nov 26 2019

Status

approved