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1, 9, 57, 369, 2481, 17049, 118377, 825729, 5771361, 40373289, 282534297, 1977503889, 13841818641, 96890604729, 678227855817, 4747575858849, 33232973616321, 232630643127369, 1628413985330937, 11398896347634609
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OFFSET
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0,2
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LINKS
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FORMULA
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G.f.: 1/(1-7*x)+1/(1-3*x)-1/(1-x). E.g.f.: e^(7*x)+e^(3*x)-e^x.
a(0)=1, a(1)=9, a(2)=57, a(n)=11*a(n-1)-31*a(n-2)+21*a(n-3). - Harvey P. Dale, Nov 09 2012
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MATHEMATICA
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Table[7^n+3^n-1, {n, 0, 20}] (* or *) LinearRecurrence[{11, -31, 21}, {1, 9, 57}, 20] (* Harvey P. Dale, Nov 09 2012 *)
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PROG
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CROSSREFS
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Cf. A155588, A155590, A155592, A155593, A155594, A155596, A155597, A155598, A155599, A155600, A155601, A155602, A155603, A155604.
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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