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A123108
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a(0)=1, a(1)=0, a(2)=1, a(3)=1, a(n)=a(n-1)+a(n-2)-a(n-3) for n>3.
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2
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1, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 28, 28, 29, 29, 30, 30, 31, 31, 32, 32, 33, 33, 34, 34, 35, 35, 36, 36, 37, 37
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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COMMENTS
| Diagonal sums of triangle A123110. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 08 2009]
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FORMULA
| G.f.: (1-x+x^3)/(1-x-x^2+x^3)
a(n)=A110654(n-1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 18 2008
a(n)=1/4[1-(-1)^(n-1)]+1/2*(n-1)+[C(2*n,n) mod 2] [From Paolo P. Lava (paoloplava(AT)gmail.com), Nov 19 2008]
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CROSSREFS
| Cf. A065033.
Sequence in context: A076938 A004526 A140106 * A008619 A110654 A109728
Adjacent sequences: A123105 A123106 A123107 * A123109 A123110 A123111
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KEYWORD
| nonn
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 28 2006
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