a(n) = 61*n^2.

Terms

a(0) =0a(1) =61a(2) =244a(3) =549a(4) =976a(5) =1525a(6) =2196a(7) =2989a(8) =3904a(9) =4941a(10) =6100a(11) =7381a(12) =8784a(13) =10309a(14) =11956a(15) =13725a(16) =15616a(17) =17629a(18) =19764a(19) =22021a(20) =24400a(21) =26901a(22) =29524a(23) =32269a(24) =35136a(25) =38125a(26) =41236a(27) =44469a(28) =47824a(29) =51301