[seqfan] Re: Another surprising omission from OEIS

[Michael Porter]

I wasn't able to find it.  I did find A053696, numbers that are repunits (as opposed to repdigits) with at least 3 digits in some base.

- Michael




--- On Tue, 11/10/09, Andrew Weimholt <andrew.weimholt at gmail.com> wrote:

From: Andrew Weimholt <andrew.weimholt at gmail.com>
Subject: [seqfan]  Another surprising omission from OEIS
To: "Sequence Fanatics Discussion list" <seqfan at list.seqfan.eu>
Date: Tuesday, November 10, 2009, 5:58 PM

Numbers that are repdigits with length > 2 in some base.
(length > 2 because all numbers n > 2, are trivially represented as 11
in base n-1)

       7 = 111     base 2
      13 = 111     base 3
      15 = 1111    base 2
      21 = 111     base 4
      26 = 222     base 3
      31 = 11111   base 2 (also 111 base 5)
      40 = 1111    base 3
      42 = 222     base 4
      43 = 111     base 6
      57 = 111     base 7
      62 = 222     base 5
      63 = 111111  base 2 (also 333 base 4)
      73 = 111     base 8
      80 = 2222    base 3
      85 = 1111    base 4
      86 = 222     base 6
      91 = 111     base 9
      93 = 333     base 5
     111 = 111     base 10
     114 = 222     base 7
     121 = 11111   base 3
     124 = 444     base 5
     127 = 1111111 base 2
     129 = 333     base 6
     133 = 111     base 11

7, 13, 15, 21, 26, 31, 40, 42, 43, 57, 62, 63, 73, 80, 85, 86,
91, 93, 111, 114, 121, 124, 127, 129, 133, 146, 156, 157,
170, 171, 172, 182, 183, 211, 215, 219, 222, 228, 241, 242,
255, 259, 266, 273, 285, 292, 307, 312, 314, 333, 341, 342,
343, 364, 365, 366, 381, 399, 400, 421, 422, 438, 444, 455,
463, 468, 471, 482, 507, 511, 518, 532, 546, 549, 553, 555,
585, 601, 614, 624, 628, 633, 637, 651, 665, 666, 682, 686,
703, 723, 728, 732, 757, 762, 777, 781, 785, 798, 800, 813,
819, 820, 842, 844, 871, 888, 915, 921, 926, 931, 942, 964,
993, 999, 1014, 1023, 1029, 1036, 1055, 1057, 1064, 1092,
1093, 1098, 1099,1106, 1111

Andrew


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