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A171470
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a(n) = 6*a(n-1) - 8*a(n-2) for n > 2; a(0) = 11, a(1) = 90, a(2) = 372.
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6
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11, 90, 372, 1512, 6096, 24480, 98112, 392832, 1572096, 6289920, 25162752, 100657152, 402640896, 1610588160, 6442401792, 25769705472, 103079018496, 412316467200, 1649266655232, 6597068193792, 26388275920896
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OFFSET
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0,1
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COMMENTS
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Related to Reverse and Add trajectory of 22 in base 2: A061561(4*n) = 2*a(n).
Binary representation of a(n) for n > 0 is given by the following production rules of the contextfree grammar: S -> 101 T 0, T -> 1 T 0 | 101. - A.H.M. Smeets, Feb 11 2019
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LINKS
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FORMULA
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a(n) = 24*4^n-3*2^n for n > 0.
G.f.: (1+4*x)*(11-20*x)/((1-2*x)*(1-4*x)).
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PROG
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(PARI) {m=21; v=concat([11, 90, 372], vector(m-3)); for(n=4, m, v[n]=6*v[n-1]-8*v[n-2]); v}
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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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