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 A068822 #16 Nov 05 2018 14:10:50 %S A068822 1,2,1,2,5,2,1,2,1,10,1,4,1,2,5,4,1,2,1,20,1,2,1,4,25,2,1,4,1,10,1,4, %T A068822 1,2,5,4,1,2,1,20,1,2,1,4,5,2,1,4,1,50,1,4,1,2,5,4,1,2,1,20,1,2,1,4,5, %U A068822 2,1,4,1,10,1,4,1,2,25,4,1,2,1,20,1,2 %N A068822 a(n) = gcd(n,c(n)), where c(n) is the 10's complement of n. %H A068822 Alois P. Heinz, <a href="/A068822/b068822.txt">Table of n, a(n) for n = 1..9999</a> %F A068822 a(n) = gcd(n,A089186(n)) = gcd(n,A178914(n)). - _Alois P. Heinz_, Nov 05 2018 %e A068822 a(45) = 5 as 10's complement of 45 is 100-45 = 55 and (45,55) = 5. %p A068822 a:=n-> igcd((10^length(n)-n), n): %p A068822 seq(a(n), n=1..100); # _Alois P. Heinz_, Sep 22 2015 %t A068822 GCD[#, 10^(IntegerLength[#]) - #] & /@ Range[82] (* _Jayanta Basu_, Aug 07 2013 *) %Y A068822 Cf. A089186, A178914. %K A068822 nonn,base,easy %O A068822 1,2 %A A068822 _Amarnath Murthy_, Mar 08 2002