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 A289287 #12 Jul 24 2017 12:54:29
%S A289287 1,8,11,81,82,7,2,71,83,6,3,61,84,5,4,51,85,41,86,31,87,21,88,12,72,
%T A289287 73,62,74,52,75,42,76,32,77,22,78,13,63,64,53,65,43,66,33,67,23,68,14,
%U A289287 54,55,44,56,34,57,24,58,15,45,46,35,47,25,48,16,36,37,26,38,17,27,28,18,19
%N A289287 Starting with a(1) = 1, a(n) = smallest nonnegative integer not yet in the sequence such that the last digit of a(n-1) plus the first digit of a(n) is equal to 9. The digit 0 is not allowed.
%C A289287 The number of terms of this finite sequence is the ninth central polygonal number, n = 73.
%t A289287 Module[{a = {1}, k, d = 9}, TimeConstrained[Do[k = 2; While[Or[MemberQ[a, k], MemberQ[IntegerDigits@ k, 0], # != d] &[Mod[a[[n - 1]], 10] + First@ IntegerDigits@ k], k++]; AppendTo[a, k], {n, 2, 100}], 2]; a] (* _Michael De Vlieger_, Jul 14 2017 *)
%Y A289287 Cf. A002061, A289283, A289284, A289285, A289286.
%K A289287 nonn,base,fini,full
%O A289287 1,2
%A A289287 _Enrique Navarrete_, Jul 01 2017