a(n,m) tabl head (triangle) for A116868 (called Y(1,3)) n\m 1 2 3 4 5 6 7 8 9 10 ... 0 1 0 0 0 0 0 0 0 0 0 1 3 4 0 0 0 0 0 0 0 0 2 9 21 25 0 0 0 0 0 0 0 3 27 90 165 190 0 0 0 0 0 0 4 81 351 846 1416 1606 0 0 0 0 0 5 243 1296 3834 8082 12900 14506 0 0 0 0 6 729 4617 16119 40365 79065 122583 137089 0 0 0 7 2187 16038 64395 185490 422685 790434 1201701 1338790 0 0 8 6561 54675 247860 804330 2072385 4443687 8048790 12065160 13403950 0 9 19683 183708 927288 3340278 9557433 22888494 47034864 83230344123442194136846144 . . . Row sums give A116862: [1,7,55,472,4300,40861,400567,4021720,41147398,427470430,...] ############################################### e.o.f.########################################