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A152982
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Sum of proper divisors of Motzkin number A001006(n).
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2
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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; internal format)
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OFFSET
| 0,4
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FORMULA
| a(n) = A001065(A001006(n)).
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EXAMPLE
| a(6)=21 because A001006(6)=51, having as proper divisors 1, 3 and 17. [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 31 2008]
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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); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 31 2008]
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CROSSREFS
| Cf. A001065, A001006, A152762, A152981, A152983.
Sequence in context: A049977 A000677 A110865 * A001642 A001643 A005218
Adjacent sequences: A152979 A152980 A152981 * A152983 A152984 A152985
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KEYWORD
| nonn
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Dec 20 2008
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EXTENSIONS
| Extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 31 2008
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