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a(n) = floor((1/2 * (sqrt(2) + 1 + sqrt(2*sqrt(2) - 1)))^n ).
1

%I #13 Sep 08 2022 08:44:58

%S 1,1,3,6,12,23,44,84,158,297,561,1056,1989,3746,7056,13287,25023,

%T 47125,88746,167127,314735,592710,1116193,2102019,3958531,7454720,

%U 14038755,26437833,49787820,93760597,176570285,332517781,626198652,1179259497

%N a(n) = floor((1/2 * (sqrt(2) + 1 + sqrt(2*sqrt(2) - 1)))^n ).

%H G. C. Greubel, <a href="/A050243/b050243.txt">Table of n, a(n) for n = 0..1000</a>

%t Table[Floor[((Sqrt[2]+1+Sqrt[2Sqrt[2]-1])/2)^n],{n,0,40}] (* _Harvey P. Dale_, Aug 07 2016 *)

%o (PARI) vector(50, n, n--; floor((1/2*(sqrt(2)+1+sqrt(2*sqrt(2)-1)))^n )) \\ _G. C. Greubel_, Sep 30 2018

%o (Magma) [Floor((1/2*(Sqrt(2)+1+Sqrt(2*Sqrt(2)-1)))^n ): n in [0..50]]; // _G. C. Greubel_, Sep 30 2018

%K nonn,easy

%O 0,3

%A Antreas P. Hatzipolakis (xpolakis(AT)otenet.gr), Dec 21 1999

%E More terms from _David W. Wilson_, Dec 22 1999