A038340 Second line of 5-wave sequence A038201.

1, 4, 9, 50, 105, 616, 1287, 7601, 15873, 93819, 195910, 1158052, 2418195, 14294449, 29849041, 176444054, 368442700, 2177943781, 4547886208, 26883530748, 56137003923, 331837870408, 692929213991, 4096053203771, 8553197751125

Offset: 0

Author

Floor van Lamoen

Keywords

• nonn
• easy

Links

• F. v. Lamoen, Wave sequences
• Index entries for linear recurrences with constant coefficients, signature (0,15,0,-35,0,28,0,-9,0,1).

Programs

Maple

a:= n-> (Matrix([`if`(irem(n,2)=0, [9, 1, 0, -1, -4], [4, 0, -1, -3, -9])]). Matrix(5, (i,j)-> if i=j-1 then 1 elif j=1 then [15, -35, 28, -9, 1][i] else 0 fi)^iquo(n+1, 2))[1,2]: seq(a(n), n=0..24); # Alois P. Heinz, Jul 16 2009

Formula

G.f.: (x^7+x^6-6*x^5-5*x^4+10*x^3+6*x^2-4*x-1) / (x^10-9*x^8+28*x^6-35*x^4+15*x^2-1). - Alois P. Heinz, Jul 16 2009