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Natural numbers listed in three columns: if A004526(n-1) = 0 then row n lists A004526(n-1), A004526(n), 1, otherwise row n lists 1, A004526(n), A004526(n-1).
1

%I #9 Nov 28 2021 02:41:21

%S 0,0,1,0,1,1,1,1,1,1,2,1,1,2,2,1,3,2,1,3,3,1,4,3,1,4,4,1,5,4,1,5,5,1,

%T 6,5,1,6,6,1,7,6,1,7,7,1,8,7,1,8,8,1,9,8,1,9,9,1,10,9,1,10,10,1,11,10,

%U 1,11,11,1,12,11,1,12,12,1,13,12,1,13,13,1,14,13,1,14,14,1,15,14,1,15,15

%N Natural numbers listed in three columns: if A004526(n-1) = 0 then row n lists A004526(n-1), A004526(n), 1, otherwise row n lists 1, A004526(n), A004526(n-1).

%C The sum of row n is equal to n. See A004526 (integers repeated), which is the main entry for this sequence. - _Omar E. Pol_, Mar 19 2008

%C As a flat sequence, a(n+1) is the number of free trees of n vertices which have the maximum possible terminal Wiener index for n vertices (A349704). [Gutman, Furtula, Petrović, theorem 5] - _Kevin Ryde_, Nov 27 2021

%H Ivan Gutman, Boris Furtula and Miroslav Petrović, <a href="https://doi.org/10.1007/s10910-008-9476-2">Terminal Wiener Index</a>, Journal of Mathematical Chemistry, volume 46, 2009, pages 522-531.

%e Rows begin:

%e n=1: 0, 0, 1;

%e n=2: 0, 1, 1;

%e n=3: 1, 1, 1;

%e n=4: 1, 2, 1;

%e n=5: 1, 2, 2;

%e n=6: 1, 3, 2;

%e ...

%Y Cf. A004526, A349704 (maximum terminal Wiener).

%K nonn,easy

%O 1,11

%A _Paul Curtz_, Oct 08 2007

%E Edited by _Omar E. Pol_, Mar 19 2008