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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
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). - 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
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified February 24 11:15 EST 2024. Contains 370303 sequences. (Running on oeis4.)