A123539 - OEIS

%I #15 Oct 16 2017 02:05:17

%S 0,1,2,1,3,1,4,1,1,5,1,1,6,1,1,1,7,1,1,1,8,1,1,1,6,9,1,1,1,10,10,1,1,

%T 1,15,1,11,1,1,1,21,6,12,1,1,1,28,21,0,13,1,1,1,36,56,0,14,1,1,1,45,

%U 126,0,0,15,1,1,1,55,252,0,0

%N Irregular triangle t(n,m) = binomial(n-m, n-binomial(m, floor(m/2))), read by rows, 0 <= m <= n/2.

%D F. R. K. Chung and R. L. Graham, Erdos on Graphs, AK Peters Ltd., Ma, 1998, page 90

%H G. C. Greubel, <a href="/A123539/b123539.txt">Table of n, a(n) for the first 100 rows, flattened</a>

%e The triangle starts:

%e    0;

%e    1;

%e    2,  1;

%e    3,  1;

%e    4,  1,  1;

%e    5,  1,  1;

%e    6,  1,  1,  1;

%e    7,  1,  1,  1;

%e    8,  1,  1,  1,  6;

%e    9,  1,  1,  1, 10;

%e   10,  1,  1,  1, 15,  1;

%p A123539 := proc(n,m)

%p         binomial(n-m,n-binomial(m,floor(m/2))) ;

%p end proc: # _R. J. Mathar_, May 12 2013

%t t[n_, m_] := Binomial[n - m, n - Binomial[m, Floor[m/2]]] a0 = Table[Table[t[n, m], {m, 0, Floor[n/2]}], {n, 0, 10}] Flatten[a0]

%Y Cf. A001405.

%K nonn,tabf

%O 0,3

%A _Roger L. Bagula_, Nov 11 2006