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A027050 a(n) = T(n,2n-1), T given by A027023. 2
1, 3, 5, 11, 25, 59, 145, 367, 949, 2495, 6645, 17883, 48541, 132711, 365073, 1009647, 2805365, 7827167, 21918997, 61584891, 173550677, 490408623, 1389206065, 3944231887, 11221911849, 31989733339, 91354992405, 261322661051 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..750

FORMULA

Conjecture D-finite with recurrence (-n+1)*a(n) +3*(2*n-3)*a(n-1) +(-7*n+10)*a(n-2) +2*(-4*n+19)*a(n-3) +(5*n-23)*a(n-4) +(2*n-5)*a(n-5) +3*(n-4)*a(n-6)=0. - R. J. Mathar, Jun 24 2020

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(T(n, 2*n-1), n=1..30); # G. C. Greubel, Nov 05 2019

MATHEMATICA

T[n_, k_]:= T[n, k]= If[n<0, 0, If[k<3 || k==2*n, 1, Sum[T[n-1, k-j], {j, 3}]]]; Table[T[n, 2*n-1], {n, 30}] (* G. C. Greubel, Nov 05 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))

[T(n, 2*n-1) for n in (1..30)] # G. C. Greubel, Nov 05 2019

CROSSREFS

Cf. A027023.

Sequence in context: A285184 A018008 A104545 * A240148 A109249 A196423

Adjacent sequences:  A027047 A027048 A027049 * A027051 A027052 A027053

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified September 22 21:04 EDT 2021. Contains 347608 sequences. (Running on oeis4.)