A019487 a(n) = 3*a(n-1) - a(n-2) + 2*a(n-3) - 2*a(n-4).

2, 6, 17, 48, 135, 379, 1064, 2987, 8385, 23538, 66075, 185483, 520680, 1461631, 4103029, 11517850, 32332423, 90762215, 254783864, 715218523, 2007731289, 5636018642, 15821193955, 44412588755, 124673147016, 349977202919

Offset

0,1

References

R. K. Guy, personal communication.

Links

Table of n, a(n) for n=0..25.

Index entries for linear recurrences with constant coefficients, signature (3,-1,2,-2).

Formula

G.f.: ( 2+x^2-x^3 ) / ( 1-3*x+x^2-2*x^3+2*x^4 ). - R. J. Mathar, Feb 11 2016

Mathematica

LinearRecurrence[{3, -1, 2, -2}, {2, 6, 17, 48}, 30] (* Harvey P. Dale, May 13 2019 *)

Crossrefs

Cf. A018915.

Sequence in context: A299166 A136776 A018915 * A077936 A077983 A365244

Adjacent sequences: A019484 A019485 A019486 * A019488 A019489 A019490

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved