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A240277
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Minimal number of people such that exactly n days are required to spread gossip.
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2
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1, 2, 4, 3, 5, 9, 17, 33, 65, 129, 257, 513, 1025, 2049, 4097, 8193, 16385, 32769, 65537, 131073, 262145, 524289, 1048577, 2097153, 4194305, 8388609, 16777217, 33554433, 67108865, 134217729, 268435457, 536870913, 1073741825, 2147483649, 4294967297
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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COMMENTS
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for n > 2: a(n) = 2^(n-2) + 1, cf. A000051.
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LINKS
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FORMULA
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a(n) = 3*a(n-1) - 2*a(n-2) for n > 4.
G.f.: (4*x^4 - 5*x^3 - x + 1)/((x - 1)*(2*x - 1)). (End)
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PROG
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(Haskell)
import Data.List (elemIndex); import Data.Maybe (fromJust)
a240277 = (+ 1) . fromJust . (`elemIndex` a007456_list)
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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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