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 A249032 #27 Jun 23 2025 10:54:23 %S A249032 3,6,4,5,5,6,4,6,4,6,4,5,5,6,4,5,5,6,4,5,5,6,4,6,4,6,4,5,5,6,4,6,4,6, %T A249032 4,5,5,6,4,6,4,6,4,5,5,6,4,5,5,6,4,5,5,6,4,6,4,6,4,5,5,6,4,5,5,6,4,5, %U A249032 5,6,4,6,4,6,4,5,5,6,4,5,5,6,4,5,5,6 %N A249032 First differences of A075326. %C A249032 Can be constructed as follows. Apart from the initial "3", one always has either "6-4" (i.e., a 6 followed by a 4), or else "5-5". The 6-4's always come either alone (6-4) or triply (6-4, 6-4, 6-4), while the 5-5's always come alone. So if we let "6-4, 5-5" be represented by the numeral "1", and "6-4, 6-4, 6-4, 5-5" by the numeral "3", then the sequence of first differences, in this compressed code, is A080426, which itself is defined by a simple substitution rule. - D. R. Hofstadter, Oct 23 2014 %H A249032 Reinhard Zumkeller, <a href="/A249032/b249032.txt">Table of n, a(n) for n = 0..10000</a> %H A249032 Robbert Fokkink and Gandhar Joshi, <a href="https://arxiv.org/abs/2506.13337">Anti-recurrence sequences</a>, arXiv:2506.13337 [math.NT], 2025. See pp. 2, 18. %H A249032 D. R. Hofstadter, <a href="/A075326/a075326_1.pdf">Anti-Fibonacci numbers</a>, Oct 23 2014 %H A249032 Thomas Zaslavsky, <a href="/A075326/a075326_2.pdf">Anti-Fibonacci Numbers: A Formula</a>, Sep 26 2016 %o A249032 (Haskell) %o A249032 a249032 n = a249032_list !! n %o A249032 a249032_list = zipWith (-) (tail a075326_list) a075326_list %o A249032 -- _Reinhard Zumkeller_, Oct 26 2014 %o A249032 (Python) %o A249032 def A249032(n): return 4+int((n+1|(~((m:=n>>1)+1)&m).bit_length())&1^1)+int((n|(~((k:=n-1>>1)+1)&k).bit_length())&1) if n else 3 # _Chai Wah Wu_, Sep 11 2024 %Y A249032 Cf. A075326, A080426, A249031. %K A249032 nonn %O A249032 0,1 %A A249032 _N. J. A. Sloane_, Oct 26 2014