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

0,2

Links

Table of n, a(n) for n=0..25.

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.

Crossrefs

Sequence in context: A026124 A026153 A025180 * A116950 A111017 A116408

Adjacent sequences: A201964 A201965 A201966 * A201968 A201969 A201970

Keyword

easy,nonn

Author

Philippe Deléham, Dec 07 2011

Status

approved