A168216 Riordan array (1/(1-x),xc(x)/(1-xc(x))) where c(x)is the g.f. of A000108.It factorizes as A007318*A106566.

1, 1, 1, 1, 3, 1, 1, 8, 5, 1, 1, 23, 19, 7, 1, 1, 74, 69, 34, 9, 1, 1, 262, 256, 147, 53, 11, 1, 1, 993, 986, 615, 265, 76, 13, 1, 1, 3943, 3935, 2571, 1235, 431, 103, 15, 1, 1, 16178, 16169, 10862, 5591, 2216, 653, 134, 17, 1

Offset

0,5

Comments

Inverse is Riordan array (1/(1+x-x^2),x(1-x)/(1+x-x^2)) = [ -1,-1,1,0,0,0,0,0,...]DELTA[1,0,0,0,0,0,0,0,...] where DELTA is the operator defined in A084938. Unsigned version of A091698.

Links

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

Formula

Sum_{k, 0<=k<=n}T(n,k)*x^k = A000012(n), A007317(n+1), A026375(n) for x = 0, 1, 2 respectively.

Example

Triangle begins : 1 ; 1,1 ; 1,3,1 ; 1,8,5,1 ; 1,23,19,7,1 ; ...

Crossrefs

Cf. A000108, A007318, A106566.

Sequence in context: A122897 A117425 A287215 * A091698 A134380 A263859

Adjacent sequences: A168213 A168214 A168215 * A168217 A168218 A168219

Keyword

nonn,tabl

Author

Philippe Deléham, Nov 20 2009

Status

approved