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A049859 a(n) = Sum_{k=0,1,2,...,n-4,n-2,n-1} a(k); a(n-3) is not a summand; 3 initial terms required. 0
0, 1, 3, 4, 7, 12, 23, 43, 81, 151, 282, 526, 982, 1833, 3422, 6388, 11925, 22261, 41556, 77575, 144814, 270333, 504647, 942055, 1758591, 3282868, 6128328, 11440120, 21355963, 39866466, 74421140, 138926437, 259342371, 484130068 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..33.

FORMULA

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

G.f.: x*(x - 1)*(2*x + 1)/(x^4 - x^3 + 2*x - 1). - Chai Wah Wu, Jul 29 2020

CROSSREFS

Sequence in context: A108700 A325851 A062202 * A124636 A231337 A049930

Adjacent sequences:  A049856 A049857 A049858 * A049860 A049861 A049862

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified December 4 22:42 EST 2021. Contains 349526 sequences. (Running on oeis4.)