A268526 a(n) = r*a(ceiling(n/2))+s*a(floor(n/2)) with a(1)=1 and (r,s)=(3,2).

1, 5, 17, 25, 61, 85, 109, 125, 233, 305, 377, 425, 497, 545, 593, 625, 949, 1165, 1381, 1525, 1741, 1885, 2029, 2125, 2341, 2485, 2629, 2725, 2869, 2965, 3061, 3125, 4097, 4745, 5393, 5825, 6473, 6905, 7337, 7625, 8273, 8705, 9137, 9425, 9857, 10145, 10433, 10625, 11273, 11705, 12137, 12425

Offset: 1

Author

N. J. A. Sloane, Feb 16 2016

Keywords

• nonn

Links

• K.-N. Chang and S.-C. Tsai, Exact solution of a minimal recurrence, Inform. Process. Lett. 75 (2000), 61-64.

Crossrefs

Sequences of form a(n) = r*a(ceiling(n/2))+s*a(floor(n/2)) with a(1)=1 and (r,s) = (1,1), (1,2), (2,1), (1,3), (2,2), (3,1), (1,4), (2,3), (3,2), (4,1): A000027, A006046, A064194, A130665, A073121, A268524, A116520, A268525, A268526, A268527.

Programs

Magma

[n le 1 select 1 else 3*Self(Ceiling(n/2))+2*Self(Floor(n/2)): n in [1..60]]; // Vincenzo Librandi, Aug 30 2016

PARI

a(n) = if (n==1, 1, 3*a(ceil(n/2))+2*a(floor(n/2))); \\ Michel Marcus, Aug 30 2016