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A147704
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Diagonal sums of Riordan array ((1-2x)/(1-3x+x^2),x(1-x)/(1-3x+x^2)).
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1
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1, 1, 3, 8, 23, 66, 190, 547, 1575, 4535, 13058, 37599, 108262, 311728, 897585, 2584493, 7441751, 21427668, 61698511, 177653782, 511533678, 1472902523, 4241053787, 12211627683, 35161980526, 101244887791
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Diagonal sums of A147703.
Hankel transform is := 1,2,3,0,0,0,0,0,0,0,... [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 15 2008]
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FORMULA
| G.f.: (1-x^2)/(1-3x+x^3);
a(n)=3*a(n-1)-a(n-3), n>2 ; a(0)=1, a(1)=1, a(2)=3 . [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 15 2008]
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CROSSREFS
| Sequence in context: A176880 A078054 A018043 * A116410 A199841 A106606
Adjacent sequences: A147701 A147702 A147703 * A147705 A147706 A147707
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Nov 10 2008
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