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 A086009 #11 Dec 15 2017 17:36:31 %S A086009 0,1,0,0,1,0,0,0,0,1,1,2,1,1,1,0,0,0,0,1,0,1,0,0,0,0,0,0,0,1,0,1,1,1, %T A086009 2,1,1,1,1,2,1,2,1,1,1,0,2,0,0,1,0,1,0,0,1,0,1,0,0,1,0,1,0,0,0,0,0,0, %U A086009 0,1,0,1,1,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,1,1,1,0,0,0,0,1,0,0,1,1,2,1,1,2 %N A086009 Number of 1's in decimal expansion of n^2. %H A086009 G. C. Greubel, <a href="/A086009/b086009.txt">Table of n, a(n) for n = 0..1000</a> %e A086009 4^2 = 16, so a(4)=1 and 11^2 = 121, so a(11)=2. %t A086009 DigitCount[(Range[0, 100])^2, 10, 1] (* _G. C. Greubel_, Dec 13 2016 *) %o A086009 (PARI) A086009(n)=#select(d->d==1,digits(n^2)) \\ _M. F. Hasler_, Feb 21 2016 %Y A086009 Cf. 0's A086008, 2's A086010, 3's A086011, 4's A086012, 5's A086013, 6's A086014, 7's A086015, 8's A086016, 9's A086017. %Y A086009 Cf. A269241 for the n^3 analog. %K A086009 base,nonn %O A086009 0,12 %A A086009 _Jason Earls_, Jul 07 2003