A168151 Riordan array (1/u,(1-u)/2), u=sqrt(1-4x+4*x^3).

1, 2, 1, 6, 3, 1, 18, 9, 4, 1, 58, 29, 13, 5, 1, 192, 96, 44, 18, 6, 1, 650, 325, 151, 64, 24, 7, 1, 2232, 1116, 524, 228, 90, 31, 8, 1, 7746, 3873, 1833, 813, 333, 123, 39, 9, 1, 27096, 13548, 6452, 2904, 1222, 473, 164, 48, 10, 1

Offset

0,2

Comments

T(n,0) = A157004(n).

References

Baccherini, D.; Merlini, D.; Sprugnoli, R. Binary words excluding a pattern and proper Riordan arrays. Discrete Math. 307 (2007), no. 9-10, 1021--1037. MR2292531 (2008a:05003). See Example 5.6. - N. J. A. Sloane, Mar 25 2014

Links

Table of n, a(n) for n=0..54.

Formula

T(n,0)=2*T(n,1) for n>0, T(0,0)=1, T(n,k)=T(n-1,k-1)-T((n-3,k-1)+T(n,k+1).

Example

Triangle begins :
1
2 1
6 3 1
18 9 4 1
58 29 13 5 1
192 96 44 18 6 1
650 325 151 64 24 7 1
...

Crossrefs

Cf. A025262, A157004

Sequence in context: A046803 A280789 A121468 * A213221 A180281 A187888

Adjacent sequences: A168148 A168149 A168150 * A168152 A168153 A168154

Keyword

nonn,tabl

Author

Philippe Deléham, Nov 19 2009

Status

approved