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 A385533 #15 Jul 09 2025 10:17:17 %S A385533 -1,-1,0,0,0,1,1,1,2,2,2,3,3,4,4,4,5,5,5,6,6,6,7,7,7,8,8,8,9,9,9,10, %T A385533 10,11,11,11,12,12,12,13,13,13,14,14,14,15,15,15,16,16,17,17,17,18,18, %U A385533 18,19,19,19,20,20,20,21,21,21,22,22,22,23,23,24,24,24 %N A385533 Third prepended column of the tribonacci array of the second kind, A385436. %C A385533 The numbers that occur thrice in this sequence are given by A353084(n)-1, i.e., the first prepended column of the tribonacci array of the first kind minus one. %H A385533 A.H.M. Smeets, <a href="/A385533/b385533.txt">Table of n, a(n) for n = 1..20000</a> %Y A385533 Cf. A353084, A385436. %K A385533 sign %O A385533 1,9 %A A385533 _A.H.M. Smeets_, Jul 02 2025