Sum of first k numbers in column k of the natural number array A000027; by antidiagonals.

Terms

a(0) =1a(1) =7a(2) =25a(3) =62a(4) =125a(5) =221a(6) =357a(7) =540a(8) =777a(9) =1075a(10) =1441a(11) =1882a(12) =2405a(13) =3017a(14) =3725a(15) =4536a(16) =5457a(17) =6495a(18) =7657a(19) =8950a(20) =10381a(21) =11957a(22) =13685a(23) =15572a(24) =17625a(25) =19851a(26) =22257a(27) =24850a(28) =27637a(29) =30625