A167704 a(0)=1, a(1)=0, a(2)=2, a(3)=1, a(n)=a(n-2)+a(n-3)+a(n-4) for n>3.

1, 0, 2, 1, 3, 3, 6, 7, 12, 16, 25, 35, 53, 76, 113, 164, 242, 353, 519, 759, 1114, 1631, 2392, 3504, 5137, 7527, 11033, 16168, 23697, 34728, 50898, 74593, 109323, 160219, 234814, 344135, 504356, 739168, 1083305, 1587659, 2326829, 3410132, 4997793, 7324620

Offset: 0

Author

Philippe Deléham, Nov 10 2009

Keywords

• nonn

Comments

Diagonal sums of triangle in A122950.

Links

• G. C. Greubel, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (0, 1, 1, 1).

Programs

Mathematica

LinearRecurrence[{0,1,1,1},{1,0,2,1},50] (* Harvey P. Dale, Aug 09 2015 *)

Formula

G.f.: (1-x^3)/(1-x^2-x^3-x^4).

a(n) = a(n-2) + a(n-3) + a(n-4). - G. C. Greubel, Jun 20 2016

Extensions

Corrected and extended by Harvey P. Dale, Aug 09 2015