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 A237583 #10 Mar 05 2020 07:03:27 %S A237583 0,1,3,4,9,28,81,136,1216,6561,16768,29889,76545,203392,636417, %T A237583 1043200,3995649,6082048,24151041,36315136,326481921,689278977, %U A237583 1487503360,11573190657,76876660737,155240824833,314944159744,785129144320,2035980763137,4857090670593 %N A237583 Automorphic numbers: n^2 ends with n in base 6. %H A237583 Eric M. Schmidt, <a href="/A237583/b237583.txt">Table of n, a(n) for n = 1..1000</a> %e A237583 From A201821: %e A237583 a(3) = (3)_6 = 3 since 3^2 = 9 = (13)_6 ends with 3 in base 6. %e A237583 a(4) = (4)_6 = 4 since 4^2 = 16 = (24)_6 ends with 4 in base 6. %e A237583 a(5) = (13)_6 = 9 since 9^2 = 81 = (213)_6 ends with 13 in base 6. %o A237583 (Sage) # See A003226. %o A237583 (PARI) isok(n) = ((n^2-n) % 6^(#digits(n, 6))) == 0; \\ _Michel Marcus_, Mar 08 2014 %Y A237583 Cf. A201821 (written in base 6), A003226, A201918, A201919, A201921, A201948. %K A237583 nonn,base %O A237583 1,3 %A A237583 _Eric M. Schmidt_, Feb 09 2014