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A152982 Sum of proper divisors of Motzkin number A001006(n). 2
0, 0, 1, 3, 4, 11, 21, 1, 37, 173, 1648, 3610, 1, 25125, 139086, 474576, 284493, 984021, 6536394, 24265740, 18678381, 96214041, 277799337, 1282283505, 2077807083, 1899874619, 19252363864, 44221482398, 1967547359, 29743945411, 1265868629 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..30.

FORMULA

a(n) = A001065(A001006(n)).

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

CROSSREFS

Cf. A001065, A001006, A152762, A152981, A152983.

Sequence in context: A049977 A000677 A110865 * A001642 A001643 A247171

Adjacent sequences:  A152979 A152980 A152981 * A152983 A152984 A152985

KEYWORD

nonn

AUTHOR

Omar E. Pol, Dec 20 2008

EXTENSIONS

Extended by Emeric Deutsch, Dec 31 2008

STATUS

approved

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Last modified November 13 08:18 EST 2019. Contains 329093 sequences. (Running on oeis4.)