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 A062033 #14 Apr 10 2025 07:06:16 %S A062033 0,10,1000,1010,100000,100010,101000,101010,10000000,10000010, %T A062033 10001000,10001010,10100000,10100010,10101000,10101010,1000000000, %U A062033 1000000010,1000001000,1000001010,1000100000,1000100010,1000101000,1000101010,1010000000,1010000010,1010001000 %N A062033 Binary expansion of n does not contain 1-bits at even positions. Integers whose base 4 representation consists of only 0's and 2s. %o A062033 (Python) %o A062033 def A062033(n): return int(bin(int(bin(n)[2:],4))[2:])*10 # _Chai Wah Wu_, Aug 21 2023 %Y A062033 Decimal representation is given in A062880. %Y A062033 Cf. A063010. %K A062033 nonn,base %O A062033 0,2 %A A062033 _Antti Karttunen_, Jun 26 2001 %E A062033 More terms from _Chai Wah Wu_, Aug 22 2023