This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A290969 #77 Aug 27 2017 10:06:01 %S A290969 1,7,31,32767,4095,435356467,16777215,68719476735,281474976710655 %N A290969 The least positive integer that is a repdigit with length > 2 in exactly n bases. %C A290969 a(10) <= 1152921504606846975 = 2^60 - 1. %C A290969 a(7) and following terms > 3*10^9. - _Giovanni Resta_, Aug 16 2017 %C A290969 a(7) <= 2^36-1 and a(8) <= 2^48-1. - _Michel Marcus_, Aug 17 2017 %C A290969 In fact, we have equality in both cases. - _Rémy Sigrist_, Aug 21 2017 %C A290969 Except for a(5) = (6^12 - 1) / 5, all the numbers in the data through a(8) are Mersenne numbers A000225. - _Bernard Schott_, Aug 27 2017 %e A290969 a(1) = 7 = 111_2. %e A290969 a(2) = 31 = 11111_2 = 111_5. %e A290969 a(3) = 32767 = (R_15)_2 = 77777_8 = (31,31,31)_32. %Y A290969 Cf. A000225, A053696, A125134, A167782, A167783, A290869. %K A290969 nonn,base,more %O A290969 0,2 %A A290969 _Bernard Schott_, Aug 16 2017 %E A290969 a(7) from _Rémy Sigrist_, Aug 19 2017 %E A290969 a(8) from _Rémy Sigrist_, Aug 21 2017