The smallest triangular number that contains the digits of n in its exact middle.

Terms

a(0) =1a(1) =120a(2) =3a(3) =741a(4) =153a(5) =6a(6) =171a(7) =780a(8) =190a(9) =10a(10) =111156a(11) =1128a(12) =131328a(13) =2145a(14) =15a(15) =3160a(16) =1176a(17) =4186a(18) =101926a(19) =152076a(20) =21a(21) =1225a(22) =102378a(23) =3240a(24) =5253a(25) =7260a(26) =1275a(27) =28a(28) =232903a(29) =113050