14032080domain: NAppears in sequencesa(n) = 1*2*3*4*5*6 + 7*8*9*10*11*12 + 13*14*15*16*17*18 + ... + (up to n).at n=17A319207a(n) = 6*5*4*3*2*1 + 12*11*10*9*8*7 + 18*17*16*15*14*13 + ... + (up to the n-th term).at n=17A319870Table T(n,k) read by upward antidiagonals. T(n,k) = Sum_{i=1..n} Product_{j=1..k} (i-1)*k+j.at n=33A333446