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0, 2, 6, 18, 52, 146, 406, 1126, 3124, 8684, 24202, 67640, 189576, 532786, 1501254, 4240550, 12005780, 34063896, 96844082, 275848044, 787104288, 2249633916, 6439678858, 18460717684, 52994100984, 152323413890, 438363476086
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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2,2
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LINKS
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FORMULA
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Conjecture D-finite with recurrence (n+1)*a(n) +2*(-4*n-1)*a(n-1) +(19*n-5)*a(n-2) +6*(-n-5)*a(n-3) +3*(-7*n+41)*a(n-4) +2*(4*n-29)*a(n-5) +(n+1)*a(n-6) +6*(n-5)*a(n-7)=0. - R. J. Mathar, Jun 15 2020
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MAPLE
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T:= proc(n, k) option remember;
if k<0 or k>2*n then 0
elif k=0 or k=2 or k=2*n then 1
elif k=1 then 0
else add(T(n-1, k-j), j=1..3)
fi
end:
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MATHEMATICA
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T[n_, k_]:= T[n, k]= If[k<0 || k>2*n, 0, If[k==0 || k==2 || k==2*n, 1, If[k==1, 0, Sum[T[n-1, k-j], {j, 3}]]]]; Table[T[n, 2*n-3], {n, 2, 30}] (* G. C. Greubel, Nov 06 2019 *)
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PROG
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(Sage)
@CachedFunction
def T(n, k):
if (k<0 or k>2*n): return 0
elif (k==0 or k==2 or k==2*n): return 1
elif (k==1): return 0
else: return sum(T(n-1, k-j) for j in (1..3))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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