A069700 Triangular numbers with internal digits 9.

0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 190, 496, 595, 990, 5995

Offset: 1

Author

Amarnath Murthy, Apr 06 2002

Keywords

• fini
• full
• nonn
• base

Comments

For proof of finiteness see A069693.

Crossrefs

Cf. A069675 to A069684, A069693 to A069700.

Programs

Mathematica

Do[ If[ Union[ Drop[ RotateLeft[ IntegerDigits[n(n + 1)/2]], -2]] == {9}, Print[n(n + 1)/2]], {n, 14, 10^6}]