A049863 a(n) = Sum{a(k): k=0,1,2,...,n-4,n-2,n-1}; a(n-3) is not a summand; initial terms are 0,3,4.

0, 3, 4, 7, 11, 21, 39, 74, 138, 258, 481, 898, 1676, 3129, 5841, 10904, 20355, 37998, 70933, 132415, 247187, 461439, 861396, 1608020, 3001788, 5603619, 10460614, 19527460, 36453089, 68049183, 127031520, 237137411, 442678728, 826375119, 1542644347, 2879747377

Offset

0,2

Links

Table of n, a(n) for n=0..35.

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).

G.f.: (x^3+2x^2-3x)/(x^4-x^3+2x-1). - Harvey P. Dale, Apr 26 2011

Mathematica

LinearRecurrence[{2, 0, -1, 1}, {0, 3, 4, 7}, 40] (* or *) CoefficientList[ Series[(x^3+2x^2-3x)/(x^4-x^3+2x-1), {x, 0, 50}], x] (* Harvey P. Dale, Apr 26 2011 *)

Crossrefs

Sequence in context: A378275 A361907 A072255 * A025068 A049928 A002364

Adjacent sequences: A049860 A049861 A049862 * A049864 A049865 A049866

Keyword

nonn,easy,changed

Author

Clark Kimberling

Status

approved