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A027178
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a(n) = T(n,0) + T(n,1) + ... + T(n,n), T given by A027170.
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2
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1, 6, 20, 52, 120, 260, 544, 1116, 2264, 4564, 9168, 18380, 36808, 73668, 147392, 294844, 589752, 1179572, 2359216, 4718508, 9437096, 18874276, 37748640, 75497372, 150994840, 301989780, 603979664, 1207959436, 2415918984
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OFFSET
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0,2
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COMMENTS
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Define a triangle U(n,k) with U(n,0) = n*(n+1) + 1 for n>=0 and U(r,c) = U(r-1,c-1) + U(r-1,c). The sum of the terms in row n is a(n). The first rows are 1; 3, 3; 7, 6, 7; 13, 13, 13, 13; 21, 26, 26, 26, 21; row sums are 1, 6, 20, 52, 120. - J. M. Bergot, Feb 15 2013
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LINKS
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FORMULA
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a(n) = 9*2^n - 4n - 8 (conjectured). - Ralf Stephan, Feb 13 2004
a(n) = 4*a(n-1)-5*a(n-2)+2*a(n-3) for n>2.
G.f.: (1+x)^2 / ((1-x)^2*(1-2*x)).
(End)
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CROSSREFS
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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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