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A005053
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Expand (1-2x)/(1-5x).
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7
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1, 3, 15, 75, 375, 1875, 9375, 46875, 234375, 1171875, 5859375, 29296875, 146484375, 732421875, 3662109375, 18310546875, 91552734375, 457763671875, 2288818359375, 11444091796875, 57220458984375
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| a(n) is the number of generalized compositions of n when there are 2^(i+1) different types of i, (i=1,2,...). [From Milan R. Janjic (agnus(AT)blic.net), Sep 24 2010]
a(n) is the number of generalized compositions of n when there are 3*2^(i-1) different types of i, (i=1,2,...). [From Milan R. Janjic (agnus(AT)blic.net), Sep 24 2010]
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LINKS
| Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 883
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FORMULA
| Binomial transform of A122117 . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 19 2006
a(0)=1, a(n)=3*5^(n-1) for n>=1 . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 19 2006
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MAPLE
| with(finance):seq(ceil(futurevalue(3, 4, n)), n=-1..19); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 25 2009]
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MATHEMATICA
| CoefficientList[Series[(1-2x)/(1-5x), {x, 0, 30}], x] (* or *) Join[{1}, NestList[5#&, 3, 29]] (* From Harvey P. Dale, Apr 25 2011 *)
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PROG
| (MAGMA) [ n eq 0 select 1 else 3*5^(n-1): n in [0..20] ];
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CROSSREFS
| Sequence in context: A151326 A063000 A002902 * A183411 A136778 A000266
Adjacent sequences: A005050 A005051 A005052 * A005054 A005055 A005056
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| Wrong formula deleted and MAGMA program added by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Apr 04 2010
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