login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (3,-2).

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

Adjacent sequences: A140501 A140502 A140503 * A140505 A140506 A140507

KEYWORD

nonn,easy

AUTHOR

Paul Curtz, Jun 30 2008

EXTENSIONS

More terms from Stefan Steinerberger, Aug 04 2008

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 3 07:58 EST 2022. Contains 358515 sequences. (Running on oeis4.)