Areas of a sequence of right-angled figures described below.

Terms

a(0) =1a(1) =7a(2) =23a(3) =57a(4) =118a(5) =218a(6) =370a(7) =590a(8) =895a(9) =1305a(10) =1841a(11) =2527a(12) =3388a(13) =4452a(14) =5748a(15) =7308a(16) =9165a(17) =11355a(18) =13915a(19) =16885a(20) =20306a(21) =24222a(22) =28678a(23) =33722a(24) =39403a(25) =45773a(26) =52885a(27) =60795a(28) =69560a(29) =79240