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 A108690 #8 Aug 19 2019 02:56:44 %S A108690 1,2,3,4,5,6,7,8,9,18,21,24,27,30,33,36,45,48,51,54,57,60,63,72,73,74, %T A108690 75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,99,102,105,108,111, %U A108690 114,117,126,129,132,135,138,141,144,153,154,155,156,157,158,159,160 %N A108690 Square roots of the terms in A080160. %p A108690 b:=n->sum(convert(((10^(n+1)-1)/9)^2,base,10)[j],j=1..2*n+1): a:=proc(n) if type(sqrt(b(n)), integer)=true then sqrt(b(n)) else fi end:seq(a(n),n=0..2000); # _Emeric Deutsch_, Jun 19 2005 %Y A108690 Cf. A080160. %K A108690 nonn,base %O A108690 1,2 %A A108690 _N. J. A. Sloane_, Jun 19 2005 %E A108690 More terms from _Emeric Deutsch_, Jun 19 2005