Triangular numbers composed of digits {1,2,6}.

Terms

a(0) =1a(1) =6a(2) =21a(3) =66a(4) =666a(5) =2211a(6) =6216a(7) =212226a(8) =222111a(9) =1222266a(10) =1261666a(11) =16626261a(12) =22121226a(13) =22221111a(14) =121111266a(15) =126222216a(16) =661261161a(17) =2162616261a(18) =2221211226a(19) =2222211111a(20) =21166222626a(21) =66126661611a(22) =166122226621a(23) =216262612611a(24) =222212111226a(25) =222222111111