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 A283558 #14 Feb 06 2025 21:32:58
%S A283558 1,1,3,2,2,6,6,48,60,168,144,288,1872,3744,5760,11520,161280,322560,
%T A283558 1866240,2903040,10782720,8294400,24883200,282009600,846028800,
%U A283558 3060633600,9181900800,10450944000,31352832000,668860416000,1881169920000,17850212352000,41009504256000,248816074752000,381752082432000
%N A283558 The number of positive integer sequences of length n with no duplicate substrings of length greater than 1 and a minimal sum (= A259280(n)).
%e A283558 For n = 7 the a(7) = 6 sequences are
%e A283558 1,3,1,2,2,1,1;
%e A283558 1,2,2,1,3,1,1;
%e A283558 1,3,1,1,2,2,1;
%e A283558 1,1,3,1,2,2,1;
%e A283558 1,2,2,1,1,3,1; and
%e A283558 1,1,2,2,1,3,1.
%t A283558 s[1] = 1; s[n_] := Ceiling[(n+1+ Sum[Floor[Sqrt[2 k] + 1/2], {k, n-1}])/2]; subQ[w_] := Block[{n = Length@w}, Length@ Union@ Flatten[ Table[ Take[w, {i, j}], {j, 2, n}, {i, j - 1}], 1] == n (n-1)/2]; a[n_] := Sum[ Length@ Select[ Permutations@ e, subQ], {e, IntegerPartitions[ s[n], {n}]}]; Array[a, 10] (* _Giovanni Resta_, Mar 10 2017 *)
%Y A283558 A283557 is the product analog.
%Y A283558 Cf. A259280, A284431, A284432, A284433.
%K A283558 nonn
%O A283558 1,3
%A A283558 _Peter Kagey_, Mar 10 2017
%E A283558 a(11)-a(13) from _Giovanni Resta_, Mar 10 2017
%E A283558 Terms a(14) onward from _Max Alekseyev_, Feb 06 2025