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1, 6, 6, 20, 15, 42, 28, 72, 45, 110, 66, 156, 91, 210, 120, 272, 153, 342, 190, 420, 231, 506, 276, 600, 325, 702, 378, 812, 435, 930, 496, 1056, 561, 1190, 630, 1332, 703, 1482, 780, 1640, 861, 1806, 946, 1980, 1035, 2162, 1128, 2352, 1225, 2550, 1326
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Also period length divided by 2 of pairs (a,b), where a has period 2n-2 and b has period n.
a(2*n) = A000384(n+1); a(2*n+1) = A026741(n+1). [Reinhard Zumkeller, Dec 12 2011]
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LINKS
| Reinhard Zumkeller, Table of n, a(n) for n = 0..10000
M. Kaneko, The Akiyama-Tanigawa algorithm for Bernoulli numbers, J. Integer Sequences, 3 (2000), #00.2.9.
Source
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FORMULA
| G.f.: (2x^3+3x^2+6x+1)/(1-x^2)^3.
a(n) = (n+1)*(n+2) if n odd; or (n+1)*(n+2)/2 if n even = (n+1)*(n+2)*(3-(-1)^n)/4 - C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 16 2004
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MAPLE
| seq((n+1)*(n+2)*(3-(-1)^n)/4, n=0..20); (C. Ronaldo)
with(combinat):seq(lcm(n+1, binomial(n+2, n)), n=0..50); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 20 2008
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MATHEMATICA
| Table[ LCM[ 2*n-2, n ]/2, {n, 40} ]
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PROG
| (Haskell)
import Data.Ratio ((%), denominator)
a045896 n = denominator $ n % ((n + 1) * (n + 2))
-- Reinhard Zumkeller, Dec 12 2011
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CROSSREFS
| Cf. A045895, A026741.
Cf. Factor of A160466. [Johannes W. Meijer, May 24 2009]
Sequence in context: A161787 A092297 A073096 * A115046 A004983 A034695
Adjacent sequences: A045893 A045894 A045895 * A045897 A045898 A045899
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KEYWORD
| nonn,easy,frac,nice
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AUTHOR
| Ralf W. Grosse-Kunstleve (rwgk(AT)cci.lbl.gov)
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