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A140323 First differences of A140322. 3
1, 9, 31, 129, 511, 2049, 8191, 32769, 131071, 524289, 2097151, 8388609, 33554431, 134217729, 536870911, 2147483649, 8589934591, 34359738369, 137438953471, 549755813889, 2199023255551, 8796093022209, 35184372088831, 140737488355329, 562949953421311 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
Mix A004171(2*n)-1, A004171(2*n+1)+1.
a(n+1)-4*a(n) = period 2: repeat [5, -5].
G.f.: x*(1 + 6*x)/(1 - 3*x - 4*x^2). - Ilya Gutkovskiy, May 11 2016
From Klaus Purath, Aug 03 2020: Start)
a(n) = 8*A015521(n-1) + A102900(n-1).
a(n) = 30*4^(n-3) + a(n-2), n>2.
a(n+2) = 3*a(n+1) + 4*a(n).
(End)
MATHEMATICA
a[n_] := (2*4^n - (-1)^n); Array[a, 25, 0] (* Robert G. Wilson v, Aug 13 2011 *)
CROSSREFS
Cf. A140322.
Sequence in context: A048374 A226274 A184054 * A160653 A189436 A145950
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, May 26 2008
EXTENSIONS
Extended and offset changed from 0 to 1 by Vincenzo Librandi, Aug 09 2011
STATUS
approved

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Last modified February 29 14:40 EST 2024. Contains 370425 sequences. (Running on oeis4.)