Smallest triangular number that begins with n.

Terms

a(0) =1a(1) =21a(2) =3a(3) =45a(4) =55a(5) =6a(6) =78a(7) =820a(8) =91a(9) =10a(10) =1128a(11) =120a(12) =136a(13) =1431a(14) =15a(15) =1653a(16) =171a(17) =1830a(18) =190a(19) =2016a(20) =21a(21) =2211a(22) =231a(23) =2415a(24) =253a(25) =2628a(26) =276a(27) =28a(28) =2926a(29) =300