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A362438
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a(n) = n^2 + 2^(n-1).
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1
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2, 6, 13, 24, 41, 68, 113, 192, 337, 612, 1145, 2192, 4265, 8388, 16609, 33024, 65825, 131396, 262505, 524688, 1049017, 2097636, 4194833, 8389184, 16777841, 33555108, 67109593, 134218512, 268436297, 536871812, 1073742785, 2147484672, 4294968385, 8589935748, 17179870409, 34359739664, 68719478105, 137438954916
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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REFERENCES
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GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 79.
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LINKS
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FORMULA
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a(n) = 5*a(n-1) - 9*a(n-2) + 7*a(n-3) - 2*a(n-4) for n > 4.
G.f.: x*(-x^3 + x^2 - 4*x + 2)/((x - 1)^3*(2*x - 1)). (End)
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PROG
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(Python)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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