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A049860 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. 1
0, 1, 4, 5, 9, 15, 29, 54, 102, 190, 355, 662, 1236, 2307, 4307, 8040, 15009, 28018, 52303, 97637, 182265, 340245, 635156, 1185684, 2213388, 4131865, 7713202, 14398700, 26878923, 50176509, 93667520, 174854817, 326412048 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Conjecture: g.f. = (x+2*x^2-3*x^3)/(1-2*x+x^3-x^4) - Harvey P. Dale, Jun 15 2019

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.

MATHEMATICA

LinearRecurrence[{2, 0, -1, 1}, {0, 1, 4, 5}, 50] (* Harvey P. Dale, Jun 15 2019 *)

CROSSREFS

Sequence in context: A042489 A217685 A251632 * A010382 A138673 A087948

Adjacent sequences:  A049857 A049858 A049859 * A049861 A049862 A049863

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified October 21 07:40 EDT 2021. Contains 348149 sequences. (Running on oeis4.)