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A095864 Largest n-digit triangular number. 6
6, 91, 990, 9870, 99681, 998991, 9997156, 99991011, 999961560, 9999878910, 99999957291, 999999911791, 9999997965180, 99999998250180, 999999997764120, 9999999895728690, 99999999552805215, 999999998765257141 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Triangular number with index given by A095863.

LINKS

Table of n, a(n) for n=1..18.

FORMULA

a(n) = A068093(n+1) - A068092(n+1).

MATHEMATICA

Join[{6}, (#(#+1))/2&/@Table[Floor[(Sqrt[8*10^n+1]-1)/2], {n, 2, 30}]] (* Harvey P. Dale, Jul 27 2012 *)

triInverse[n_] := Floor[(Sqrt[1 + 8*n] - 1)/2]; tri[n_] := n*(n+1)/2; Table[tri[triInverse[10^n - 1]], {n, 18}] (* T. D. Noe, Jul 27 2012 *)

CROSSREFS

Cf. A068092, A068093, A068094, A095863, A095865, A095866.

Sequence in context: A265088 A077370 A226382 * A246155 A219220 A006151

Adjacent sequences:  A095861 A095862 A095863 * A095865 A095866 A095867

KEYWORD

base,easy,nonn

AUTHOR

Ray Chandler, Jun 28 2004

STATUS

approved

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Last modified November 19 11:09 EST 2019. Contains 329319 sequences. (Running on oeis4.)