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A141722
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a(n) = 8*4^n - 7.
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4
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1, 25, 121, 505, 2041, 8185, 32761, 131065, 524281, 2097145, 8388601, 33554425, 134217721, 536870905, 2147483641, 8589934585, 34359738361, 137438953465, 549755813881, 2199023255545, 8796093022201, 35184372088825, 140737488355321, 562949953421305
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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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a(n) = 4*a(n-1) + 21.
a(n) = 5*a(n-1) - 4*a(n-2).
E.g.f.: 8*exp(4*x) - 7*exp(x). (End)
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MAPLE
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MATHEMATICA
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PROG
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(PARI) x='x+O('x^50); Vec((1+20*x)/((1-x)*(1-4*x))) \\ G. C. Greubel, Sep 30 2017
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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