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A072262
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a(n) = 4*a(n-1)+1, a(1)=11.
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1
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11, 45, 181, 725, 2901, 11605, 46421, 185685, 742741, 2970965, 11883861, 47535445, 190141781, 760567125, 3042268501, 12169074005, 48676296021, 194705184085, 778820736341, 3115282945365, 12461131781461, 49844527125845
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| These are the integers N which on application of the Collatz function yield the number 17. The Collatz function: if N is an odd number then (3N+1)/2^r yields a positive odd integer for some value of r (which in this case is 17).
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (5,-4).
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FORMULA
| Contribution from Bruno Berselli, Dec 16 2011: (Start)
G.f.: x*(11-10*x)/(1-5*x+4*x^2).
a(n) = (17*2^(2n-1)-1)/3.
Sum(a(i), i=1..n) = (a(n+1)-n+1)/3-4. (End)
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MATHEMATICA
| a[n_] := 4a[n - 1] + 1; a[1] = 11; Table[ a[n], {n, 1, 25}]
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CROSSREFS
| Cf. A072257, A072258, A072259, A072260, A072261, A099730.
Sequence in context: A057813 A051740 A144932 * A110114 A116193 A063158
Adjacent sequences: A072259 A072260 A072261 * A072263 A072264 A072265
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KEYWORD
| nonn,easy
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AUTHOR
| N. Rathankar (rathankar(AT)yahoo.com), Jul 08 2002
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EXTENSIONS
| Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 17 2002
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