A068094 Number of n-digit triangular numbers.

3, 10, 31, 96, 306, 967, 3058, 9670, 30579, 96700, 305793, 967000, 3057922, 9670000, 30579224, 96699996, 305792239, 966999967, 3057922393, 9669999669, 30579223926, 96699996687, 305792239263, 966999966873, 3057922392627, 9669999668731, 30579223926265

Offset: 1

Author

Amarnath Murthy, Feb 19 2002

Keywords

• base
• easy
• nonn

Crossrefs

Cf. A068092, A068093, A095863, A095864, A095865, A095866.

Programs

Mathematica

triInverse[n_] := Floor[(Sqrt[1 + 8*n] - 1)/2]; Differences[Table[triInverse[10^(n - 1) - 1], {n, 30}]] (* T. D. Noe, Jul 27 2012 *)

Formula

Differences of successive terms of A068092.

Extensions

More terms from Sascha Kurz, Mar 06 2002