login
This site is supported by donations to The OEIS Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A073728 a(n) = Sum_{k=0..n} S(k), where S(n) are the tribonacci generalized numbers A001644. 1
3, 4, 7, 14, 25, 46, 85, 156, 287, 528, 971, 1786, 3285, 6042, 11113, 20440, 37595, 69148, 127183, 233926, 430257, 791366, 1455549, 2677172, 4924087, 9056808, 16658067, 30638962, 56353837, 103650866, 190643665, 350648368, 644942899 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Robert Israel, Table of n, a(n) for n = 0..3399

Daniel Birmajer, Juan B. Gil, Michael D. Weiner, Linear recurrence sequences with indices in arithmetic progression and their sums, arXiv preprint, 2015.

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

FORMULA

a(n) = a(n-1) + a(n-2) + a(n-3), a(0)=3, a(1)=4, a(2)=7.

G.f.: (3+x)/(1-x-x^2-x^3).

a(n) = 3*T(n+1)+T(n), where T(n) are the tribonacci numbers A000073.

a(n) = (S(n+3)-S(n+1))/2, where S(n) = A001644(n). - Michael D. Weiner, Mar 27 2015

MAPLE

A:= gfun[rectoproc]({a(n)=a(n-1)+a(n-2)+a(n-3), a(0)=3, a(1)=4, a(2)=7}, a(n), remember):

seq(A(n), n=0..100); # Robert Israel, Mar 26 2015

MATHEMATICA

CoefficientList[Series[(3 + x)/(1 - x - x^2 - x^3), {x, 0, 40}], x]

PROG

(MAGMA) I:=[3, 4, 7]; [n le 3 select I[n] else Self(n-1)+Self(n-2)+Self(n-3): n in [1..40]]; // Vincenzo Librandi, Mar 27 2015

CROSSREFS

Cf. A001644, A000073.

Sequence in context: A062203 A095063 A003242 * A132753 A132407 A070035

Adjacent sequences:  A073725 A073726 A073727 * A073729 A073730 A073731

KEYWORD

easy,nonn

AUTHOR

Mario Catalani (mario.catalani(AT)unito.it), Aug 06 2002

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 January 19 16:49 EST 2019. Contains 319309 sequences. (Running on oeis4.)