Number of divisors of the n-th positive number that is both triangular and square.

Terms

a(0) =1a(1) =9a(2) =9a(3) =45a(4) =9a(5) =405a(6) =15a(7) =189a(8) =81a(9) =729a(10) =27a(11) =6075a(12) =27a(13) =1215a(14) =2025a(15) =729a(16) =81a(17) =45927a(18) =27a(19) =32805a(20) =2025a(21) =6561a(22) =81a(23) =229635a(24) =243a(25) =2187a(26) =2187a(27) =18225a(28) =9a(29) =7381125