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 A163534 #17 Jul 04 2025 12:36:43 %S A163534 0,0,1,2,2,1,0,0,0,0,0,3,2,2,3,0,0,0,0,0,1,2,2,1,0,0,1,2,2,1,0,0,1,2, %T A163534 2,2,2,2,3,0,0,3,2,2,2,2,2,1,0,0,1,2,2,1,0,0,1,2,2,1,0,0,0,0,0,3,2,2, %U A163534 3,0,0,0,0,0,1,2,2,1,0,0,0,0,0,3,2,2,3,0,0,0,0,0,1,2,2,1,0,0,0,0,0,3 %N A163534 The absolute direction (0=east, 1=south, 2=west, 3=north) of the Peano curve A163334 at point n. %C A163534 Taking every ninth term gives the same sequence: (and similarly for all higher powers of 9 as well): a(n) = a(9*n). %H A163534 Antti Karttunen, <a href="/A163534/b163534.txt">Table of n, a(n) for n = 1..59049</a> %F A163534 a(n) = A010873(A163532(n)+A163533(n)+abs(A163533(n))+3). %F A163534 a(n) = A004442(A163535(n)). %o A163534 (Scheme) (define (A163534 n) (modulo (+ 3 (A163532 n) (A163533 n) (abs (A163533 n))) 4)) %Y A163534 Cf. A163535 (transposed direction), A163536 (turn). %K A163534 nonn %O A163534 1,4 %A A163534 _Antti Karttunen_, Aug 01 2009 %E A163534 Name corrected by _Kevin Ryde_, Aug 29 2020