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 A086012 #11 Dec 15 2017 17:36:31 %S A086012 0,0,1,0,0,0,0,1,1,0,0,0,2,0,0,0,0,0,1,0,1,2,2,0,0,0,0,0,1,1,0,0,1,0, %T A086012 0,0,0,0,3,0,0,0,1,1,0,0,0,0,1,1,0,0,1,0,0,0,0,1,1,1,0,0,2,0,1,1,1,2, %U A086012 2,1,1,1,1,0,1,0,0,0,1,1,1,0,1,0,0,0,0,0,2,0,0,0,2,1,0,0,0,1,1,0,0,0,2,0,0 %N A086012 Number of 4's in decimal expansion of n^2. %H A086012 G. C. Greubel, <a href="/A086012/b086012.txt">Table of n, a(n) for n = 0..1000</a> %t A086012 DigitCount[(Range[0, 100])^2, 10, 4] (* _G. C. Greubel_, Dec 13 2016 *) %o A086012 (PARI) A086012(n)=#select(d->d==4,digits(n^2)) \\ _M. F. Hasler_, Feb 21 2016 %Y A086012 Cf. 0's A086008, 1's A086009, 2's A086010, 3's A086011, 5's A086013, 6's A086014, 7's A086015, 8's A086016, 9's A086017. %Y A086012 Cf. A269244 for the n^3 analog. %K A086012 base,nonn %O A086012 0,13 %A A086012 _Jason Earls_, Jul 07 2003