%I #11 Dec 07 2019 12:18:24

%S 1,3,15,120,1365,20349,376740,8347680,215553195,6358402050,

%T 210980549208,7778680504140,315502265971620,13961746143269400,

%U 669413654240461560,34569147570568156800,1912924003884628655655,112923282067713332728110

%N Column 1 of triangle A107867; a(n) = binomial( n*(n+1)/2 + n+1, n).

%o (PARI) a(n)=binomial(n*(n+1)/2+n+1,n)

%o (Sage) [binomial(binomial(binomial(n+1,n),n-1),n-1) for n in range(1, 19)] # _Zerinvary Lajos_, Nov 30 2009

%Y Cf. A107867, A107868.

%K nonn

%O 0,2

%A _Paul D. Hanna_, Jun 04 2005