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a(n) = A002865(2*n-1)+A002865(2*n).
3

%I #12 Mar 21 2020 09:41:02

%S 1,3,6,11,20,35,58,96,154,242,375,573,861,1282,1886,2745,3961,5667,

%T 8038,11323,15836,22001,30383,41715,56953,77363,104566,140668,188397,

%U 251247,333689,441474,581890,764215,1000233,1304815,1696717,2199591,2843073,3664312

%N a(n) = A002865(2*n-1)+A002865(2*n).

%C a(n) is also the length of the n-th "large mirror" of the "mirror" version of the shell model of partitions of A135010.

%H Nathaniel Johnston, <a href="/A182845/b182845.txt">Table of n, a(n) for n = 1..1000</a>

%e a(1)=0+1=1. a(2)=1+2=3: a(3)=2+4=6. a(4)=4+7=11. a(5)=8+12=20. a(6)=14+21=35.

%Y Cf. A000041, A002865, A135010. For another version see A182844.

%K nonn,easy

%O 1,2

%A _Omar E. Pol_, Jan 24 2011

%E Extended by _Nathaniel Johnston_, May 06 2011