[seqfan] Another surprising omission from OEIS

Andrew Weimholt andrew.weimholt at gmail.com
Wed Nov 11 02:58:01 CET 2009


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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