

A199881


Triangle T(n,k), read by rows, given by (1,1,0,0,0,0,0,0,0,0,0,...) DELTA (1,0,1,1,0,0,0,0,0,0,0,...) where DELTA is the operator defined in A084938.


0



1, 1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 0, 2, 3, 1, 0, 0, 1, 4, 4, 1, 0, 0, 0, 3, 7, 5, 1, 0, 0, 0, 1, 7, 11, 6, 1, 0, 0, 0, 0, 4, 14, 16, 7, 1, 0, 0, 0, 0, 1, 11, 25, 22, 8, 1, 0, 0, 0, 0, 0, 5, 25, 41, 29, 9, 1, 0, 0, 0, 0, 0, 1, 16, 50, 63, 37, 10, 1
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OFFSET

0,9


COMMENTS

A skewed version of triangular array A072405.


LINKS

Table of n, a(n) for n=0..77.


FORMULA

T(n,k)=T(n1,k1)+T(n2,k1) starting with T(0,0)=T(1,0)=T(1,1)=T(2,1)=T(2,2)=1 and T(2,0)=0.
G.f.: (1+xy*x^2)/(1y*xy*x^2).
T(2n,n)=A028310(n).


EXAMPLE

Triangle begins :
1
1, 1
0, 1, 1
0, 1, 2, 1 (key row for starting the recurrence)
0, 0, 2, 3, 1
0, 0, 1, 4, 4, 1
0, 0, 0, 3, 7, 5, 1
0, 0, 0, 1, 7, 11, 6, 1
0, 0, 0, 0, 4, 14, 16, 7, 1


CROSSREFS

Cf. A000931 (diagonal sums), A042950(column sums), A055389 (row sums)
Sequence in context: A120730 A122851 A064301 * A060701 A275345 A259668
Adjacent sequences: A199878 A199879 A199880 * A199882 A199883 A199884


KEYWORD

nonn,tabl


AUTHOR

Philippe Deléham, Nov 11 2011


STATUS

approved



