A201967 Expansion of 1/(1-2*x-3*x^2+x^4) in powers of x.

1, 2, 7, 20, 60, 178, 529, 1572, 4671, 13880, 41244, 122556, 364173, 1082134, 3215543, 9554932, 28392320, 84367302, 250696021, 744939016, 2213573775, 6577597296, 19545219896, 58078292664, 172578671241, 512814623178

Offset: 0

Author

Philippe Deléham, Dec 07 2011

Keywords

• easy
• nonn

Links

• Index entries for linear recurrences with constant coefficients, signature (2,3,0,-1).

Formula

a(n)= 2*a(n-1) + 3*a(n-2) - a(n-4), a(0)=1, a(n)=0 if n<0.