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a(n) = (A051894(n) - 1)/2.
0

%I #9 Mar 03 2023 09:33:04

%S 0,1,4,9,21,40,79,138,250,415,707,1126,1836,2837,4466,6723,10290,

%T 15167,22672,32805,48071,68470,98610,138491,196474,272559,381540,

%U 523417,724042,983415,1345848,1811341,2454994,3276807,4402076,5830801,7769950,10219523,13516934

%N a(n) = (A051894(n) - 1)/2.

%Y Cf. A051894.

%K nonn

%O 0,3

%A _N. J. A. Sloane_, Mar 02 2023