First differences of A069473.

Terms

a(0) =540a(1) =2100a(2) =5460a(3) =11340a(4) =20460a(5) =33540a(6) =51300a(7) =74460a(8) =103740a(9) =139860a(10) =183540a(11) =235500a(12) =296460a(13) =367140a(14) =448260a(15) =540540a(16) =644700a(17) =761460a(18) =891540a(19) =1035660a(20) =1194540a(21) =1368900a(22) =1559460a(23) =1766940a(24) =1992060a(25) =2235540a(26) =2498100a(27) =2780460a(28) =3083340