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 A282169 #18 Feb 06 2025 20:43:39 %S A282169 1,2,2,6,6,24,24,120,120,576,720,2880,4320,17280,30240,120960,241920, %T A282169 967680,1935360,8709120,17418240,87091200,174182400,870912000, %U A282169 1741824000,9580032000,19160064000,104509440000,229920768000,1149603840000,2759049216000,13795246080000,33108590592000,165542952960000,430411677696000 %N A282169 a(n) is the minimal product of a positive integer sequence of length n with no duplicate substrings of length greater than 1, and every number different from its neighbors. %e A282169 [1,1] is not a valid sequence because 1 is self-adjacent. %e A282169 [1,2,3,1,2] is not valid because the substring [1,2] appears twice. %e A282169 a(1) = 1 via [1]; %e A282169 a(2) = 2 via [1,2]; %e A282169 a(3) = 2 via [1,2,1]; %e A282169 a(4) = 6 via [1,2,1,3]; %e A282169 a(5) = 6 via [1,2,1,3,1]; %e A282169 a(6) = 24 via [1,2,1,3,1,4]; %e A282169 a(7) = 24 via [1,2,1,3,1,4,1]; %e A282169 a(8) = 120 via [1,2,1,3,1,4,1,5]; %e A282169 a(9) = 120 via [1,2,1,3,1,4,1,5,1]; %e A282169 a(10) = 576 via [1,2,1,3,1,4,2,3,4,1]; %e A282169 a(11) = 720 via [1,2,1,3,1,4,1,5,1,6,1]. %Y A282169 Cf. A081456, A282164, A282193, A282170, A284434. %Y A282169 Cf. A282166 is the sum analog. %K A282169 nonn %O A282169 1,2 %A A282169 _Peter Kagey_, Feb 07 2017 %E A282169 Terms a(12) onward from _Max Alekseyev_, Feb 04 2025