A286951 - OEIS

%I #21 Sep 05 2019 19:08:29

%S 1,1,1,1,1,3,1,4,6,1,5,28,1,6,48,101,1,7,73,963,1,8,106,1818,10413,1,

%T 9,147,3383,271128,1,10,198,6129,441031,11557799

%N Irregular triangle read by rows: T(n,k) is the number of graphs with n vertices with matching number k (0 <= k <= floor(n/2)).

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/MatchingNumber.html">Matching Number</a>

%e Triangle begins:

%e   1;

%e   1;

%e   1, 1;

%e   1, 3;

%e   1, 4,  6;

%e   1, 5,  28;

%e   1, 6,  48,  101;

%e   1, 7,  73,  963;

%e   1, 8, 106, 1818, 10413;

%e   ...

%Y Row sums are A000088.

%Y T(2n,n) gives A218462 (for n>0).

%K nonn,tabf

%O 0,6

%A _Eric W. Weisstein_, May 17 2017

%E Name corrected by _Andrew Howroyd_, Nov 04 2017

%E T(0,0)=1 added by _Alois P. Heinz_, Nov 04 2017