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 A217520 #27 Nov 01 2024 01:59:46 %S A217520 2,4,8,20,7,42,16,13,40,55,25,39,84,61,64,272,22,342,80,127,110,253, %T A217520 49,500,78,40,168,812,121,930,256,166,544,420,76,666,684,118,160,328, %U A217520 253,1806,440,184,506,1081,193,2058,1000,817,312,2756,67 %N A217520 Base-3 state complexity of partitioned deterministic finite automaton (PDFA) for the periodic sequence (123...n)*. %C A217520 Also the number of distinct words that can be formed from (123..n)* by taking every 3^k-th term from some initial index i, with i and k nonnegative. (Follows from Case 2 of Theorem 2.1) - _Charlie Neder_, Feb 28 2019 %H A217520 Charlie Neder, <a href="/A217520/b217520.txt">Table of n, a(n) for n = 2..100</a> %H A217520 Klaus Sutner and Sam Tetruashvili, <a href="http://www.cs.cmu.edu/~sutner/papers/auto-seq.pdf">Inferring Automatic Sequences</a>. %F A217520 a(3^k) = (3^(k+1)-1)/2. It appears that a(n) <= n(n-1), with equality if and only if n is a prime with primitive root 3 (A019334). - _Charlie Neder_, Feb 28 2019 %Y A217520 Cf. A217519, A217521, A247566-A247581, A019334. %K A217520 nonn %O A217520 2,1 %A A217520 _N. J. A. Sloane_, Oct 07 2012 %E A217520 a(11)-a(20) added (see Inferring Automatic Sequences) by _Vincenzo Librandi_, Nov 18 2012 %E A217520 a(21)-a(54) from _Charlie Neder_, Feb 28 2019