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 A158023 #8 Mar 30 2025 13:16:24 %S A158023 1,2,3,4,6,8,10,12,14,16,17,19,20,22,23,25,26,28,29,31,32,34,35,37,38, %T A158023 40,41,43,44,46,47,49,50,52,53,200,205,210,215,220,225,230,235,240, %U A158023 245,250,255,260,265,270,275,280,285,290,295,300,305,310,315,320,325,330 %N A158023 Sides of squares which are filled exactly (no holes, no overlaps) by the digits needed to write a subsequence of consecutive nonnegative integers starting with 0. %C A158023 The integers fitting exactly in a "nonnegative-integers-digits square" are given by A158022. Terms computed by Jean-Marc Falcoz. %H A158023 Eric Angelini, <a href="http://www.cetteadressecomportecinquantesignes.com/DigitSpiral.htm">Digit Spiral</a> %H A158023 Eric Angelini, <a href="/A158022/a158022.pdf">Digit Spiral</a> [Cached copy, with permission] %e A158023 ...0...01...012...0123...012345 %e A158023 .......23...345...4567...678910 %e A158023 ............678...8910...111213 %e A158023 ..................1112...141516 %e A158023 .........................171819 %e A158023 .........................202122 %e A158023 The above squares, filled exactly by a subsequence of nonnegative integers starting with 0, have sides 1, 2, 3, 4, 6. There is no side-5 square with this property. The next properly filled square will have side 6. %Y A158023 Cf. A158022. %K A158023 base,nonn %O A158023 1,2 %A A158023 _Eric Angelini_, Mar 11 2009