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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A130766 3n+2 sandwiched by tripled 3n+1 . 1
 1, 1, 1, 2, 4, 4, 4, 5, 7, 7, 7, 8, 10, 10, 10, 11, 13, 13, 13, 14, 16, 16, 16, 17, 19, 19, 19, 20, 22, 22, 22, 23, 25, 25, 25, 26, 28, 28, 28, 29, 31, 31, 31, 32, 34, 34, 34, 35, 37, 37, 37, 38, 40, 40, 40, 41, 43, 43, 43, 44, 46, 46, 46, 47, 49, 49, 49, 50, 52, 52, 52, 53, 55 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1). FORMULA From Chai Wah Wu, Jun 17 2016: (Start) a(n) = a(n-1) + a(n-4) - a(n-5) for n > 4. G.f.: (x^4 + x^3 + 1)/(x^5 - x^4 - x + 1). (End) a(n) = 2*floor(n/4) + floor((n+1)/4) + 1. - Ridouane Oudra, Jan 26 2024 Sum_{n>=0} (-1)^n/a(n) = Pi/(3*sqrt(3)) (A073010). - Amiram Eldar, Feb 11 2024 MATHEMATICA CoefficientList[Series[(x^4 + x^3 + 1) / (x^5 - x^4 - x + 1), {x, 0, 100}], x] (* Vincenzo Librandi, Jun 18 2016 *) LinearRecurrence[{1, 0, 0, 1, -1}, {1, 1, 1, 2, 4}, 100] (* Harvey P. Dale, Apr 18 2023 *) PROG (Magma) I:=[1, 1, 1, 2, 4]; [n le 5 select I[n] else Self(n-1)+Self(n-4)-Self(n-5): n in [1..80]]; // Vincenzo Librandi, Jun 18 2016 CROSSREFS Cf. A073010. Sequence in context: A178976 A352426 A372323 * A227190 A284581 A284560 Adjacent sequences: A130763 A130764 A130765 * A130767 A130768 A130769 KEYWORD nonn AUTHOR Paul Curtz, Aug 18 2007 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.

Last modified July 21 18:08 EDT 2024. Contains 374475 sequences. (Running on oeis4.)