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A049873 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
2, 2, 3, 5, 10, 19, 36, 67, 125, 233, 435, 812, 1516, 2830, 5283, 9862, 18410, 34367, 64155, 119762, 223567, 417346, 779085, 1454365, 2714951, 5068163, 9461046, 17661506, 32969800, 61546717, 114892974, 214477654, 400378391 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..32.

FORMULA

a(n)=2*a(n-1)-a(n-3)+a(n-4); 4 initial terms required.

MATHEMATICA

LinearRecurrence[{2, 0, -1, 1}, {2, 2, 3, 5}, 40] (* Harvey P. Dale, May 08 2017 *)

CROSSREFS

Sequence in context: A344708 A322113 A153900 * A127180 A317809 A249241

Adjacent sequences:  A049870 A049871 A049872 * A049874 A049875 A049876

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified September 19 22:06 EDT 2021. Contains 347576 sequences. (Running on oeis4.)