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%I #7 Aug 30 2016 02:05:15
%S 1,5,21,25,89,105,121,125,381,445,509,525,589,605,621,625,1649,1905,
%T 2161,2225,2481,2545,2609,2625,2881,2945,3009,3025,3089,3105,3121,
%U 3125,7221,8245,9269,9525,10549,10805,11061,11125,12149,12405,12661,12725,12981,13045,13109,13125,14149,14405
%N a(n) = r*a(ceiling(n/2))+s*a(floor(n/2)) with a(1)=1 and (r,s)=(4,1).
%H K.-N. Chang and S.-C. Tsai, <a href="http://dx.doi.org/10.1016/S0020-0190(00)00076-4">Exact solution of a minimal recurrence</a>, Inform. Process. Lett. 75 (2000), 61-64.
%o (PARI) a(n) = if (n==1, 1, 4*a(ceil(n/2))+a(floor(n/2))); \\ _Michel Marcus_, Aug 30 2016
%Y 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.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Feb 16 2016