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 A071133 #5 Aug 01 2018 10:28:39
%S A071133 16,400,900,1600,29584,70627216,394618225,2214643600,4982948100,
%T A071133 8858574400,16052636601,64210546404,169556179984,727092173809,
%U A071133 1120597967889,2908368695236,6543829564281,6703226505481,79822717134736,407103419654416,12766762698010000
%N A071133 Squares which repeat with at least two full periods when written in base 7.
%H A071133 Giovanni Resta, <a href="/A071133/b071133.txt">Table of n, a(n) for n = 1..39</a> (terms < 7^29)
%e A071133 19865^2 = 394618225 = 12531|12531|1 in base 7.
%e A071133 411772^2 = 169556179984 = 1515152|1515152 in base 7.
%t A071133 psq[b_, nd_] := Block[{sq={}, r, x}, Do[r = Mod[nd, p]; Do[x = (b^( Floor[nd/p] p) - 1)/(b^p - 1) t b^r + Floor[t/b^(p - r)]; If[ IntegerQ@ Sqrt@ x, AppendTo[ sq, x]], {t, b^(p - 1), b^p - 1}], {p, nd/2}]; sq]; Union @@ (psq[7, #] & /@ Range[12]) (* _Giovanni Resta_, Aug 01 2018 *)
%Y A071133 Cf. A071128 (base 2) - A071135 (base 9), A069919 (base 10).
%K A071133 base,nonn
%O A071133 1,1
%A A071133 _Erich Friedman_, May 28 2002
%E A071133 a(17)-a(21) from _Giovanni Resta_, Aug 01 2018