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A147722
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Row sums of Riordan array ((1-3x)/(1-4x+x^2), x(1-x)/(1-4x+x^2)).
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3
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1, 2, 8, 36, 164, 748, 3412, 15564, 70996, 323852, 1477268, 6738636, 30738644, 140215948, 639602452, 2917580364, 13308696916, 60708323852, 276924225428, 1263204479436, 5762173946324, 26284460772748
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OFFSET
| 0,2
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COMMENTS
| Row sums of A147721.
Hankel transform of a(n) is [1,4,0,0,0,0,0,0,...]. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 03 2008]
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FORMULA
| G.f.: (1-3x)/(1-5x+2x^2).
a(n)=5*a(n-1)-2*a(n-2), a(0)=1, a(1)=2. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 13 2008]
a(n)=(1/2)*[(5/2)+(1/2)*sqrt(17)]^n+(1/2)*[(5/2)-(1/2)*sqrt(17)]^n-(1/34)*[(5/2)+(1/2)*sqrt(17)]^n *sqrt(17)+(1/34)*sqrt(17)*[(5/2)-(1/2)*sqrt(17)]^n, with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Nov 18 2008]
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CROSSREFS
| Sequence in context: A088675 A027743 A152124 * A089387 A084868 A109980
Adjacent sequences: A147719 A147720 A147721 * A147723 A147724 A147725
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Nov 11 2008
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