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A140504 a(n) = 2^n + 4. 20
5, 6, 8, 12, 20, 36, 68, 132, 260, 516, 1028, 2052, 4100, 8196, 16388, 32772, 65540, 131076, 262148, 524292, 1048580, 2097156, 4194308, 8388612, 16777220, 33554436, 67108868, 134217732, 268435460, 536870916, 1073741828 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
LINKS
FORMULA
G.f.: (5 - 9*x)/((1 - x)*(1 - 2*x)). - Jaume Oliver Lafont, Aug 30 2009
a(n) = 2*a(n-1) - 4 with a(0) = 5. - Vincenzo Librandi, Nov 24 2009
From Reinhard Zumkeller, Feb 28 2010: (Start)
a(n) = A173786(n,2) for n > 1.
a(n+2)*A028399(n) = A175164(2*n). (End)
From G. C. Greubel, Jul 08 2021: (Start)
a(n) = m*(2^(n-2) + 1), with m = 4.
E.g.f.: exp(2*x) + 4*exp(x). (End)
MATHEMATICA
Table[2^n + 4, {n, 0, 30}] (* Stefan Steinerberger, Aug 04 2008 *)
LinearRecurrence[{3, -2}, {5, 6}, 40] (* Harvey P. Dale, May 26 2018 *)
PROG
(Sage) [2^n + 4 for n in range(0, 31)] # Zerinvary Lajos, May 31 2009
(PARI) a(n)=2^n+4 \\ Charles R Greathouse IV, Dec 21 2011
(Magma) [2^n +4: n in [0..30]]; // G. C. Greubel, Jul 08 2021
CROSSREFS
Cf. A000051 (m=0), A052548 (m=2), this sequence (m=4), A153973 (m=6), A231643 (m=5), A175161 (m=8), A175162 (m=16), A175163 (m=32).
Sequence in context: A193569 A032721 A105106 * A120131 A047437 A188054
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Jun 30 2008
EXTENSIONS
More terms from Stefan Steinerberger, Aug 04 2008
STATUS
approved

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Last modified April 23 07:11 EDT 2024. Contains 371905 sequences. (Running on oeis4.)