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 A276575 #14 Dec 30 2018 10:41:34 %S A276575 0,3,3,2,3,4,1,2,3,3,3,3,2,3,3,2,3,2,3,3,2,3,3,4,1,3,3,2,3,3,2,3,2,3, %T A276575 2,3,3,3,3,3,3,4,3,2,3,3,3,2,3,3,2,3,4,1,3,2,3,3,3,2,2,3,3,3,2,3,3,4, %U A276575 3,3,3,3,3,2,3,4,3,3,3,3,2,3,3,4,2,3,4,3,2,3,3,4,1,3,2,3,3,3,2,3,2,3,3,3,2,3,3,2,2,3,3,2,3,3,3,3,2,3,3,2,3 %N A276575 After a(0)=0, the first differences of A276573. %H A276575 Antti Karttunen, <a href="/A276575/b276575.txt">Table of n, a(n) for n = 0..10028</a> %H A276575 Burkard Polster, <a href="https://www.youtube.com/watch?v=f1yDExNAEMg">Root 2 and the deadly Marching Squares</a>, Mathologer video (2015) %F A276575 a(n) = A002828(A276573(n)). %F A276575 a(0) = 0; for n >= 1, a(n) = A276573(n) - A276573(n-1). %F A276575 Other identities. %F A276575 For all n >= 1, a(A260731(A132592(n))) = a(A260733(A001541(n))) = 2. [This is implied by the fact observed in the Polster video. Of course 2's occur at other points too.] %o A276575 (Scheme, two alternatives) %o A276575 (define (A276575 n) (A002828 (A276573 n))) %o A276575 (define (A276575 n) (if (zero? n) n (- (A276573 n) (A276573 (- n 1))))) %Y A276575 Cf. A001541, A002828, A132592, A260731, A260733, A276573. %K A276575 nonn %O A276575 0,2 %A A276575 _Antti Karttunen_, Sep 07 2016