login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A049871 a(n)=Sum{a(k): k=0,1,2,...,n-4,n-2,n-1}; a(n-3) is not a summand; 3 initial terms required. 0
1, 3, 3, 6, 10, 20, 37, 70, 130, 243, 453, 846, 1579, 2948, 5503, 10273, 19177, 35799, 66828, 124752, 232882, 434735, 811546, 1514962, 2828071, 5279331, 9855246, 18397383, 34343506, 64111097, 119680057, 223413991, 417060391 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..32.

Index entries for linear recurrences with constant coefficients, signature (2, 0, -1, 1).

FORMULA

a(n)=2*a(n-1)-a(n-3)+a(n-4); 4 initial terms required.

G.f.: (x^3-3*x^2+x+1)/(-x^4+x^3-2*x+1) [From Harvey P. Dale, Nov 09 2011]

MATHEMATICA

LinearRecurrence[{2, 0, -1, 1}, {1, 3, 3, 6}, 40] (* Harvey P. Dale, Nov 09 2011 *)

CROSSREFS

Sequence in context: A031504 A298164 A304265 * A049924 A049926 A298954

Adjacent sequences:  A049868 A049869 A049870 * A049872 A049873 A049874

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 24 22:46 EDT 2021. Contains 347651 sequences. (Running on oeis4.)