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Search: id:A083746
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| A083746 |
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a(1) = 1, a(2) = 2; for n>2, a(n) = 3*(n-2)*(n-2)!. |
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+0
5
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| 1, 2, 3, 12, 54, 288, 1800, 12960, 105840, 967680, 9797760, 108864000, 1317254400, 17244057600, 242853811200, 3661488230400, 58845346560000, 1004293914624000, 18140058832896000, 345728180109312000, 6933770723303424000
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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a(1) = 1, a(2)=2, define S(k) = sum of all the terms other than a(k) k <n. a(n) = Sum S(k), k = 1 to n-1.
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FORMULA
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a(n) = (n-2)* {Sum (a(i)): (i = 1 to (n-1))}.
E.g.f.: 3*(x-2)*ln(1-x)-5*x+x^2. - Vladeta Jovovic (vladeta(AT)Eunet.yu), May 06 2003
SUM(a(k): 1<=k<=n) = A052560(n-1); for n>2: a(n) = A052673(n-2). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 14 2007
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EXAMPLE
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a(4) = {a(1) +a(2)} +{a(1) +a(3)} + {a(2) +a(3)}= 12.
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MAPLE
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a := proc(n) option remember: if n=1 then RETURN(1) fi: if n=2 then RETURN(2) fi: 3*(n-2)*(n-2)! end: for n from 1 to 40 do printf(`%d, `, a(n)) od:
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CROSSREFS
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Cf. A001563.
Cf. A129379.
Sequence in context: A009243 A002638 A027072 this_sequence A025231 A094532 A092980
Adjacent sequences: A083743 A083744 A083745 this_sequence A083747 A083748 A083749
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy and Meenakshi Srikanth (amarnath_murthy(AT)yahoo.com), May 06 2003
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EXTENSIONS
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Simpler description from Vladeta Jovovic (vladeta(AT)Eunet.yu), May 06 2003
More terms and Maple code from James A. Sellers (sellersj(AT)math.psu.edu), May 19, 2003
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