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 A280643 #10 Dec 23 2024 14:53:45 %S A280643 29,34,39,46,118,125,141,142,155,161,170,211,213,477,489,511,522,526, %T A280643 529,535,554,573,582,586,589,631,632,633,645,663,680,691,699,723,733, %U A280643 744,747,770,785,790,816,817,832,854,859,863,869,873,878,892,897,901,923 %N A280643 Numbers k such that k^3 has an odd number of digits and the middle digit is 3. %C A280643 The sequence of cubes starts: 24389, 39304, 59319, 97336, 1643032, 1953125, 2803221, 2863288, ... %H A280643 Lars Blomberg, <a href="/A280643/b280643.txt">Table of n, a(n) for n = 1..10000</a> %H A280643 Jeremy Gardiner, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2016-December/017135.html">Middle digit in cube numbers</a>, Seqfan Mailing list, Dec 12 2016. %e A280643 29^3 = 24(3)89, 161^3 = 417(3)281, 663^3 = 2914(3)4247. %t A280643 Select[Range[925],OddQ[len=Length[IntegerDigits[#^3]]]&&Part[IntegerDigits[#^3],(len+1)/2]==3 &] (* _Stefano Spezia_, Oct 03 2023 *) %Y A280643 Cf. A280640-A280642, A280644-A280649, A181354. %Y A280643 See A279420-A279429 for a k^2 version. %Y A280643 See A279430-A279431 for a k^2 version in base 2. %K A280643 nonn,base,easy %O A280643 1,1 %A A280643 _Lars Blomberg_, Jan 07 2017