A099431 Expansion of x(1-2x+3x^2)/(1-x-2x)^2;.

0, 1, 0, 6, 8, 30, 60, 154, 336, 774, 1700, 3762, 8184, 17758, 38220, 81930, 174752, 371382, 786420, 1660258, 3495240, 7340046, 15379100, 32156346, 67108848, 139810150, 290805060, 603979794, 1252698776, 2594876094, 5368709100

Offset: 0

Author

Paul Barry, Oct 15 2004

Keywords

• easy
• nonn

Comments

Convolution of A078008 and A099430(n-1)+3*0^n/2.

Links

• Index entries for linear recurrences with constant coefficients, signature (2,3,-4,-4).

Formula

a(n)=sum{k=0..n, (2^(n-k)+2(-1)^(n-k))/3*(2^(k-1)-(-1)^k-1+3*0^k/20)}; a(n)=sum{k=0..n+1, A078008(n-k)binomial(n-k+1, k)binomial(1, (k+1)/2)(1-(-1)^k)/2}.