A111806 Riordan array (1/(1+3x+2x^2),x/(1+3x+2x^2)).

1, -3, 1, 7, -6, 1, -15, 23, -9, 1, 31, -72, 48, -12, 1, -63, 201, -198, 82, -15, 1, 127, -522, 699, -420, 125, -18, 1, -255, 1291, -2223, 1795, -765, 177, -21, 1, 511, -3084, 6562, -6768, 3840, -1260, 238, -24, 1, -1023, 7181, -18324, 23276, -16758, 7266, -1932, 308, -27, 1, 2047, -16398, 49029, -74616, 65870

Offset

0,2

Comments

Signed version of A110441. Factors as (1/(1+x),x/(1+x))*((1-x)/(1+x),x(1-x)/(1+x)), or inverse binomial transform of A080246. Inverse of little Schroeder number array A110440. Row sums are A108520. Diagonal sums are (-1)^n*A001906(n+1).

Links

Table of n, a(n) for n=0..59.

Formula

T(n,k)=-3*T(n-1,k)+T(n-1,k-1)-2*T(n-2,k), T(0,0)=1, T(n,k)=0 if k<0 or if k>n. - Philippe Deléham, Jan 04 2013

Example

Triangle starts
1;
-3,1;
7,-6,1;
-15,23,-9,1;
31,-72,48,-12,1;

Crossrefs

Sequence in context: A319740 A275662 A110441 * A372118 A321163 A054458

Adjacent sequences: A111803 A111804 A111805 * A111807 A111808 A111809

Keyword

easy,sign,tabl

Author

Paul Barry, Aug 18 2005

Status

approved