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A062691 Triangular numbers that contain exactly 2 different digits. 9
10, 15, 21, 28, 36, 45, 78, 91, 171, 300, 595, 990, 1711, 2211, 3003, 5050, 5151, 5565, 5995, 6555, 8778, 10011, 66066, 222111, 255255, 333336, 500500, 600060, 828828, 887778, 1188111, 5656566, 22221111, 50005000, 51151555, 88877778, 2222211111, 5000050000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..37.

EXAMPLE

300 is triangular and contains the digits 0 and 3.

MATHEMATICA

Select[Accumulate[Range[14000]], Count[DigitCount[#], Except[0]]==2&] (* Harvey P. Dale, Nov 27 2011 *)

CROSSREFS

Cf. A213518.

Sequence in context: A098564 A168103 A322045 * A257630 A129496 A075520

Adjacent sequences:  A062688 A062689 A062690 * A062692 A062693 A062694

KEYWORD

base,easy,nonn

AUTHOR

Erich Friedman, Jul 04 2001

STATUS

approved

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Last modified August 18 08:57 EDT 2019. Contains 326077 sequences. (Running on oeis4.)