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 A237274 #12 Aug 05 2014 01:02:20 %S A237274 2,1,4,5,1,4,2,7,7,5,7,7,2,4,1,5,4,1,2,1,4,5,1,4,2,7,7,5,7,7,2,4,1,5, %T A237274 4,1,2,1,4,5,1,4,2,7,7,5,7,7,2,4,1,5,4,1,2,1,4,5,1,4,2,7,7,5,7,7,2,4, %U A237274 1,5,4,1 %N A237274 a(n) = A236283(n) mod 9. %C A237274 (Conjecture) This has period 18: repeat 2, 1, 4, 5, 1, 4, 2, 7, 7, 5, 7, 7, 2, 4, 1, 5, 4, 1. %C A237274 The first 19 terms and the following 17 are palindromes. %C A237274 The sorted terms in the conjectured period are 1, 1, 1, 1, 2, 2, 2, 4, 4, 4, 4, 5, 5, 5, 7, 7, 7, 7. %C A237274 Via the extended differences of A236283(n+1) and A236283(n+18) - A236283(n) which is A008600(n+9)=162, 180,... ,it is easy to see that A236283(0)=2. %C A237274 A236283(-n) = A236283(n). %C A237274 A236283(n) difference table: %C A237274 2, 1, 4, 5, 10, 13, 20, 25, 34, 41,... %C A237274 -1, 3, 1, 5, 3, 7, 5, 9, 7, 11,... = A097062(n+1) %C A237274 4, -2, 4, -2, 4, -2, 4, -2, 4, -2,... %C A237274 -6, 6, -6, 6, -6, 6, -6, 6, -6, 6,... . %C A237274 A097062(n+1) mod 9 = (a(n+1) -a(n)) mod 9 = %C A237274 period 18: repeat 8, 3, 1, 5, 3, 7, 5, 0, 7, 2, 0, 4, 2, 6, 4, 8, 6, 1 =b(n). b(n) + b(18-n)= 9, 9, 9, 9, 9, 9, 9, 0, 9. %C A237274 Ordered b(n)= %C A237274 period 18: repeat 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8. %F A237274 a(n) = A236283(n) mod 9. %K A237274 nonn %O A237274 0,1 %A A237274 _Paul Curtz_, Feb 05 2014