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 A363955 #13 Jun 30 2023 02:48:37 %S A363955 0,1,3,8,9,10,11,12,13,14,15,64,65,67,68,69,71,72,73,74,75,76,77,78, %T A363955 79,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112, %U A363955 113,115,116,117,119,120,121,122,123,124,125,126,127,256,257,258,259 %N A363955 When the base-2 representation of n is interpreted as a Gaussian integer x+yi in base (-1+i), both x and y are nonnegative. %D A363955 J.-P. Allouche and J. Shallit, Automatic Sequences, Cambridge, 2003, Section 14.5. %H A363955 W. Penney, <a href="https://dl.acm.org/doi/pdf/10.1145/321264.321274">A "binary" system for complex numbers</a>, J. ACM 12 (1965), 247-248. %F A363955 There is an automaton of 21 states that accepts the base-2 representation of members of this sequence. %e A363955 9 is in the sequence, since 9 in base 2 is 1001, which is 3+2i in base (-1+i). %t A363955 Select[Range[0, 260], Min[ReIm[FromDigits[IntegerDigits[#, 2], I - 1]]] >= 0 &] (* _Amiram Eldar_, Jun 29 2023 *) %Y A363955 Cf. A066321, A271472. %K A363955 nonn %O A363955 1,3 %A A363955 _Jeffrey Shallit_, Jun 29 2023