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 A048363 #21 Mar 07 2025 07:54:15 %S A048363 7,87,312,1287,10572,81103,397212,881912,5270652,7601169,134021535, %T A048363 421518419,1402775027,4204494972,42305694389,397212509427, %U A048363 1943649189427,6130065071251,76024844477168,98844816642745,1333325833012312,6069248534849827,13303299356842428,191199837283345112,1084811955030810572 %N A048363 a(n) is the index of the smallest triangular number containing exactly n 8's. %H A048363 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TriangularNumber.html">Triangular Number</a> %t A048363 nsmall = Table[Infinity, 20]; %t A048363 For[i = 0, i <= 10^6, i++, p = PolygonalNumber[i]; %t A048363 n0 = Count[IntegerDigits[p], 8]; %t A048363 If[nsmall[[n0]] > i, nsmall[[n0]] = i]]; %t A048363 ReplaceAll[nsmall, Infinity -> "?"] (* _Robert Price_, Mar 22 2020 *) %Y A048363 Cf. A036525, A048353, A048355, A048356, A048357, A048358, A048359, A048360, A048361, A048362, A048364, A048545. %K A048363 nonn,base %O A048363 1,1 %A A048363 _Patrick De Geest_, Mar 15 1999 %E A048363 a(13)-a(15) from _Lars Blomberg_, May 16 2011 %E A048363 a(16)-a(18) from _Giovanni Resta_, Oct 30 2019 %E A048363 a(19)-a(25) from _Max Alekseyev_, Mar 07 2025