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!)
A027043 a(n) = Sum_{k=0..2n} (k+1) * A027023(n,k). 2
1, 6, 23, 80, 285, 990, 3367, 11256, 37097, 120862, 390123, 1249728, 3978365, 12598350, 39718403, 124743104, 390491505, 1218875302, 3794984883, 11789335464, 36551285573, 113120066678, 349523991123, 1078402178776 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

MAPLE

T:= proc(n, k) option remember;

      if k<3 or k=2*n then 1

    else add(T(n-1, k-j), j=1..3)

      fi

    end:

seq(add((k+1)*T(n, k), k=0..2*n), n=0..30); # G. C. Greubel, Nov 04 2019

MATHEMATICA

T[n_, k_]:= T[n, k]= If[k<3 || k==2*n, 1, Sum[T[n-1, k-j], {j, 3}]]; Table[Sum[(k+1)*T[n, k], {k, 0, 2*n}], {n, 0, 30}] (* G. C. Greubel, Nov 04 2019 *)

PROG

(Sage)

@CachedFunction

def T(n, k):

    if (k<3 or k==2*n): return 1

    else: return sum(T(n-1, k-j) for j in (1..3))

[sum((k+1)*T(n, k) for k in (0..2*n)) for n in (0..30)] # G. C. Greubel, Nov 04 2019

CROSSREFS

Sequence in context: A114245 A220238 A078798 * A006815 A264690 A241394

Adjacent sequences:  A027040 A027041 A027042 * A027044 A027045 A027046

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 May 13 14:47 EDT 2021. Contains 343860 sequences. (Running on oeis4.)