Triangular numbers which remain triangular when the most significant digit is moved to the end.

Terms

a(0) =1a(1) =3a(2) =6a(3) =10a(4) =55a(5) =66a(6) =300a(7) =325a(8) =666a(9) =1035a(10) =1485a(11) =1891a(12) =61776a(13) =103740a(14) =109746a(15) =112575a(16) =190653a(17) =340725a(18) =1026028a(19) =1264845a(20) =3000025a(21) =3002475a(22) =3592540a(23) =3670695a(24) =37840650a(25) =60000535a(26) =61577253a(27) =65008503a(28) =1001393128a(29) =1432436050