A069693 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, 8001

Offset: 1

Author

Amarnath Murthy, Apr 06 2002

Keywords

• nonn
• base
• fini
• full

Examples

			The internal digits of 3003 are "00", which are both 0. 15 has no internal digits.
		

Links

• Max Alekseyev, Proof of finiteness of A069693 - A069700

Crossrefs

Cf. A069675-A069684, A069693-A069700.

Programs

Mathematica

Do[ If[ Union[ Drop[ RotateLeft[ IntegerDigits[n(n + 1)/2]], -2]] == {0}, Print[n(n + 1)/2]], {n, 14, 2 10^6}]

Extensions

Corrected by Sascha Kurz, Jan 02 2003