A049859 - OEIS

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, 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

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OFFSET

0,3

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (2,0,-1,1).

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

MATHEMATICA

LinearRecurrence[{2, 0, -1, 1}, {0, 1, 3, 4}, 40] (* Harvey P. Dale, Jan 14 2024 *)

CROSSREFS

Sequence in context: A108700 A325851 A062202 * A124636 A231337 A373805

Adjacent sequences: A049856 A049857 A049858 * A049860 A049861 A049862

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved