Triangular numbers with either no internal digits or all internal digits are 0.
0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105, 300, 406, 703, 903, 3003, 4005
1 seqfan posts
Sun Mar 15 02:46:16 CET 2009 [seqfan] A069693 .. A069700 (triangular numbers of the form abb...bc) are fini and full