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A068898 Triangular numbers containing 2n digits in which the sum of the first n digits = that of the rest. 2
55, 66, 2415, 3003, 5050, 5151, 5995, 8778, 9045, 113050, 138075, 171405, 174345, 177906, 183921, 198765, 203203, 216153, 219453, 234270, 237705, 239086, 252405, 255255, 266815, 267546, 275653, 279378, 284635, 293761, 294528, 306153, 309291, 329266, 348195 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

EXAMPLE

2415 is a member with 2+4 = 1+5

MATHEMATICA

dsQ[n_]:=Module[{idn=IntegerDigits[n], len=IntegerLength[n]/2}, Total[Take[ idn, len]] ==Total[ Take[idn, -len]]]; Select[Flatten[ Table[Table[(n(n+1))/2, {n, Ceiling[(Sqrt[8 10^i+1]-1)/2], Floor[ (Sqrt[8 10^(i+1)+1]-1)/2]}], {i, 1, 5, 2}]], dsQ] (* Harvey P. Dale, Sep 29 2011 *)

CROSSREFS

Cf. A068896, A068897.

Sequence in context: A004434 A168109 A116055 * A068899 A053719 A217236

Adjacent sequences:  A068895 A068896 A068897 * A068899 A068900 A068901

KEYWORD

easy,nonn,base

AUTHOR

Amarnath Murthy, Mar 21 2002

EXTENSIONS

Corrected and extended by Harvey P. Dale, Sep 29 2011

STATUS

approved

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Last modified November 15 21:37 EST 2019. Contains 329168 sequences. (Running on oeis4.)