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A087438
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3*2^(2(n-1))+2^(n-2)(n+1).
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1
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1, 4, 15, 56, 212, 816, 3184, 12544, 49728, 197888, 789248, 3151872, 12596224, 50360320, 201388032, 805437440, 3221504000, 12885491712, 51540852736, 206161051648, 824639225856, 3298546417664, 13194163650560, 52776608464896
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Binomial transform of A047926.
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..500
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FORMULA
| G.f.: (1-4*x+3*x^2)/((1-2*x)^2*(1-4*x)).
E.g.f.: (3*exp(4*x)+(1+2*x)*exp(2*x))/4.
a(0)=1, a(1)=4, a(2)=15, a(n)=8*a(n-1)-20*a(n-2)+16*a(n-3) [From Harvey P. Dale, May 20 2011]
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MATHEMATICA
| LinearRecurrence[{8, -20, 16}, {1, 4, 15}, 30] (* or *) CoefficientList[ Series[ (1-4x+3x^2)/((1-2x)^2(1-4x)), {x, 0, 30}], x] (* From Harvey P. Dale, May 20 2011 *)
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PROG
| (MAGMA) [3*2^(2*(n-1))+2^(n-2)*(n+1): n in [0..25]]; // Vincenzo Librandi, May 21 2011
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CROSSREFS
| Sequence in context: A158500 A001791 A047128 * A131497 A174958 A077823
Adjacent sequences: A087435 A087436 A087437 * A087439 A087440 A087441
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Sep 03 2003
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