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A062107
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Diagonal of table A062104.
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5
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0, 1, 3, 10, 30, 90, 270, 810, 2430, 7290, 21870, 65610, 196830, 590490, 1771470, 5314410, 15943230, 47829690, 143489070, 430467210, 1291401630, 3874204890, 11622614670, 34867844010, 104603532030, 313810596090, 941431788270
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OFFSET
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1,3
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LINKS
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FORMULA
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a(n) = 10*3^(n-4) for n >= 4.
G.f.: x^2(1+x^2)/(1-3x);
a(n) = Sum_{k=0..n-2} 3^(n-k-2)binomial(1, k/2)(1+(-1)^k)/2.
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MAPLE
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[seq(ChessPawnTriangle(j, j), j=1..50)];
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CROSSREFS
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Except for initial terms, same as A005052.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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