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A083597
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a(n) = (7*4^n - 4)/3.
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7
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1, 8, 36, 148, 596, 2388, 9556, 38228, 152916, 611668, 2446676, 9786708, 39146836, 156587348, 626349396, 2505397588, 10021590356, 40086361428, 160345445716, 641381782868, 2565527131476, 10262108525908, 41048434103636
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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a(n) = (7*4^n-4)/3.
G.f.: (1+3*x)/((1-4*x)*(1-x)).
E.g.f.: (7*exp(4*x)-4*exp(x))/3.
a(0)=1, a(1)=8, a(n) = 5*a(n-1) - 4*a(n-2). - Harvey P. Dale, Jul 23 2011
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MATHEMATICA
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(7*4^Range[0, 25]-4)/3 (* or *) LinearRecurrence[{5, -4}, {1, 8}, 26] (* Harvey P. Dale, Jul 23 2011 *)
CoefficientList[Series[(1 + 3 x)/((1 - 4 x) (1 - x)), {x, 0, 22}], x] (* Michael De Vlieger, Mar 03 2017 *)
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PROG
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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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