login
A106469
Expansion of (1 + x^2)*(1 + 2*x)/(1 - x^2).
1
1, 2, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4
OFFSET
0,2
FORMULA
a(0)=1, a(n)=(2-0^((n-1)/2))(1-(-1)^n)+(2-0^(n/2))(1+(-1)^n)/2, n>1.
MATHEMATICA
CoefficientList[Series[(1+x^2)(1+2x)/(1-x^2), {x, 0, 95}], x] (* James C. McMahon, Feb 02 2024 *)
CROSSREFS
Row sums of A106468.
Sequence in context: A100374 A045841 A040003 * A082508 A327730 A365348
KEYWORD
easy,nonn
AUTHOR
Paul Barry, May 03 2005
STATUS
approved