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 A152228 #6 Nov 21 2018 07:37:21 %S A152228 0,0,1,1,1,1,1,0,0,1,1,0,0,1,0,0,0,1,0,0,1,1,1,0,0,0,0,0,0,0,0,1,0,0, %T A152228 1,0,0,1,1,0,1,1,1,0,0,0,1,1,1,0,0,1,0,1,0,0,1,0,1,1,1,0,1,0,1,1,0,0, %U A152228 0,1,1,0,1,0,1,1,0,0,0,1,1,0,1,1,0,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1,1,1,0,1,0 %N A152228 2-adic expansion of log(5). %H A152228 Wikipedia, <a href="https://en.wikipedia.org/wiki/P-adic_number">p-adic number</a> %F A152228 a(n) = (A321690(n+1) - A321690(n))/2^n. - _Jianing Song_, Nov 17 2018 %e A152228 log(5) (2-adic) = ...0001110110010010000000011100100010011001111100 (base 2). %e A152228 log(5) (2-adic) = 2^2 + 2^3 + 2^4 + 2^5 + 2^6 + 2^9 + 2^10 + 2^13 +... %e A152228 exp( log(5) (2-adic) ) = 101 (base 2) = 5. %o A152228 (PARI) a(n)=(truncate( log(5+2*O(2^n)) )%2^(n+1))\2^n %Y A152228 Cf. A068434, A321690, A321694 (log(-3)). %K A152228 base,nonn %O A152228 0,1 %A A152228 _Paul D. Hanna_, Nov 29 2008