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A049866 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, 1, 3, 4, 8, 14, 27, 50, 94, 175, 327, 610, 1139, 2126, 3969, 7409, 13831, 25819, 48198, 89974, 167960, 313541, 585306, 1092626, 2039671, 3807577, 7107834, 13268623, 24769340, 46238423, 86316057, 161131397, 300793711 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

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.

MATHEMATICA

LinearRecurrence[{2, 0, -1, 1}, {1, 1, 3, 4}, 40] (* Harvey P. Dale, Jul 28 2019 *)

CROSSREFS

Sequence in context: A136425 A331330 A005907 * A118355 A026632 A332985

Adjacent sequences:  A049863 A049864 A049865 * A049867 A049868 A049869

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified May 25 11:07 EDT 2020. Contains 334592 sequences. (Running on oeis4.)