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 A104308 #15 Mar 25 2022 09:27:11 %S A104308 1,1,1,2,1,1,1,2,1,7,3,1,1,3,1,3,1,1,12,3,1,1,1,4,1,6,1,1,1,22,7,1,3, %T A104308 1,1,1,1,15,3,1,1,1,1,14,3,1,1,1,1,1,3,1,1,3,1,1,1,2,1,13,3,1,1,1,3,1, %U A104308 2,1,1,1,1,7,3,10,4,2,3,1,1,7,3,26,10,10,2,1,3,1,1,1,26,10,26,2,4,8,3,1,1,1 %N A104308 Number of perfect rulers of length n having the least possible largest difference between any adjacent marks that can occur amongst all perfect rulers of this length. %C A104308 For nomenclature related to perfect and optimal rulers see Peter Luschny's "Perfect Rulers" web pages. %H A104308 F. Schwartau, Y. Schröder, L. Wolf and J. Schoebel, <a href="/A104308/b104308.txt">Table of n, a(n) for n = 1..208</a> [a(212), a(213) commented out by _Georg Fischer_, Mar 25 2022] %H A104308 Peter Luschny, <a href="http://www.luschny.de/math/rulers/introe.html">Perfect and Optimal Rulers.</a> A short introduction. %H A104308 Hugo Pfoertner, <a href="http://www.randomwalk.de/scimath/diffset/consdifs.txt">Largest and smallest maximum differences of consecutive marks of perfect rulers.</a> %H A104308 F. Schwartau, Y. Schröder, L. Wolf and J. Schoebel, <a href="https://dx.doi.org/10.21227/cd4b-nb07">MRLA search results and source code</a>, Nov 6 2020. %H A104308 F. Schwartau, Y. Schröder, L. Wolf and J. Schoebel, <a href="https://doi.org/10.1109/OJAP.2020.3043541">Large Minimum Redundancy Linear Arrays: Systematic Search of Perfect and Optimal Rulers Exploiting Parallel Processing</a>, IEEE Open Journal of Antennas and Propagation, 2 (2021), 79-85. %H A104308 <a href="/index/Per#perul">Index entries for sequences related to perfect rulers.</a> %e A104308 a(11)=3 because 3 of the A103300(11)/2=15 perfect rulers of length 11 can be constructed using the shortest possible maximum segment length A104307(11)=3: [0,1,2,5,8,11], [0,1,4,6,9,11], [0,1,4,7,9,11], not counting their mirror images. %Y A104308 Cf. A104307 size of minimally required longest segment, A103294 definitions related to complete rulers. %K A104308 nonn %O A104308 1,4 %A A104308 _Hugo Pfoertner_, Mar 01 2005