A038249 Third line of 4-wave sequence A038197.

1, 2, 9, 19, 75, 160, 622, 1329, 5157, 11021, 42756, 91376, 354484, 757588, 2938977, 6281058, 24366645, 52075371, 202020427, 431749580, 1674922950, 3579575053, 13886550633, 29677753369, 115131438424, 246054079584, 954538564968

Offset: 0

Author

Floor van Lamoen

Keywords

• nonn
• easy

Links

• F. v. Lamoen, Wave sequences
• Index entries for linear recurrences with constant coefficients, signature (0,10,0,-15,0,7,0,-1).

Programs

Maple

a:= n-> (Matrix([[ `if`(irem(n,2)=0, 1, 2), 0, 0, 1]]). Matrix(4, (i,j)-> if i=j-1 then 1 elif j=1 then [10, -15, 7, -1][i] else 0 fi)^iquo(n, 2))[1,1]: seq(a(n), n=0..30); # Alois P. Heinz, Jul 16 2009

Formula

G.f.: (-x^3-x^2+2*x+1) / (x^8-7*x^6+15*x^4-10*x^2+1). - Alois P. Heinz, Jul 16 2009