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A048488
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a(n) = 6*2^n - 5.
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10
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1, 7, 19, 43, 91, 187, 379, 763, 1531, 3067, 6139, 12283, 24571, 49147, 98299, 196603, 393211, 786427, 1572859, 3145723, 6291451, 12582907, 25165819, 50331643, 100663291, 201326587, 402653179, 805306363, 1610612731
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OFFSET
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0,2
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COMMENTS
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a(n) = T(5, n), array T given by A048483.
Sequence is generated by the Northwest (NW) direction of circles put around circle(s). See illustration. - Odimar Fabeny, Aug 09 2008
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LINKS
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FORMULA
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a(n) = 2*a(n-1) + 5, n > 0, a(0) = 1. - Paul Barry, Aug 25 2004
Equals binomial transform of [1, 6, 6, 6, ...]. - Gary W. Adamson, Apr 29 2008
a(n) = 3*2^(1+n) - 5. a(n) = 3*a(n-1) - 2*a(n-2).
G.f.: (1+4*x)/((1-x)*(1-2*x)). (End)
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EXAMPLE
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a(2) = 6 * 2^2 - 5 = 6 * 4 - 5 = 24 - 5 = 19.
a(3) = 6 * 2^3 - 5 = 6 * 8 - 5 = 48 - 5 = 43.
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MAPLE
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MATHEMATICA
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PROG
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CROSSREFS
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n-th difference of a(n), a(n-1), ..., a(0) is (6, 6, 6, ...).
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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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