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A127849
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a(n) = 5^C(n,2)*(5^n-1)/4.
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1
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0, 1, 30, 3875, 2437500, 7626953125, 119201660156250, 9313106536865234375, 3637969493865966796875000, 7105423719622194766998291015625, 69388931933644926175475120544433593750
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OFFSET
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0,3
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COMMENTS
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-a(n) is the Hankel transform of A127848, the series reversion of x/(1+6*x+5*x^2). Note that (5^n-1)/4 has g.f. x/(1-6*x+5*x^2).
(-1)^n*a(n) is the Hankel transform of the series reversion of x*(1+4*x)/(1+2*x-3*x^2). - Paul Barry, Jul 12 2008
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LINKS
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MATHEMATICA
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Table[5^Binomial[n, 2] (5^n-1)/4, {n, 0, 20}] (* Harvey P. Dale, Dec 31 2022 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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