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 A055125 #13 Mar 31 2017 22:20:38 %S A055125 0,14,13,12,11,10,9,8,7,6,5,4,3,2,1,210,224,223,222,221,220,219,218, %T A055125 217,216,215,214,213,212,211,195,209,208,207,206,205,204,203,202,201, %U A055125 200,199,198,197,196,180,194,193,192,191,190,189,188,187,186,185,184 %N A055125 Base-15 complement of n (write n in base 15, then replace each digit with its base-15 negative). %H A055125 Alois P. Heinz, <a href="/A055125/b055125.txt">Table of n, a(n) for n = 0..3374</a> %H A055125 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %Y A055125 Cf. A004488, A048647, A055115-A055126. %Y A055125 Column k=15 of A248813. %K A055125 base,easy,nonn %O A055125 0,2 %A A055125 _Henry Bottomley_, Apr 19 2000