Smallest triangular number that contains the string n in its exact center.

Terms

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