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A068094 Number of n-digit triangular numbers. 6
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..27.

FORMULA

Differences of successive terms of A068092.

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 *)

CROSSREFS

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

Sequence in context: A106517 A055217 A097472 * A100058 A002160 A214839

Adjacent sequences:  A068091 A068092 A068093 * A068095 A068096 A068097

KEYWORD

base,easy,nonn

AUTHOR

Amarnath Murthy, Feb 19 2002

EXTENSIONS

More terms from Sascha Kurz, Mar 06 2002

STATUS

approved

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Last modified November 21 05:01 EST 2017. Contains 294988 sequences.