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A164683
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a(n) = 8*a(n-2) for n > 2; a(1) = 1, a(2) = 8.
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5
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1, 8, 8, 64, 64, 512, 512, 4096, 4096, 32768, 32768, 262144, 262144, 2097152, 2097152, 16777216, 16777216, 134217728, 134217728, 1073741824, 1073741824, 8589934592, 8589934592, 68719476736, 68719476736, 549755813888
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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a(n) = 2^(1/4*(6*n-3+3*(-1)^n)).
G.f.: x*(1+8*x)/(1-8*x^2).
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MATHEMATICA
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With[{c=8^Range[0, 15]}, Riffle[c, c]]//Rest (* Harvey P. Dale, Aug 08 2017 *)
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PROG
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(Magma) [ n le 2 select 7*n-6 else 8*Self(n-2): n in [1..26] ];
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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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STATUS
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approved
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