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 A086015 #12 Dec 15 2017 17:36:31 %S A086015 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,1,1,0,0,0,0,0, %T A086015 0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0, %U A086015 0,1,0,0,0,0,1,0,2,0,0,0,0,0,1,0,1,1,1,1,2,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 %N A086015 Number of 7's in decimal expansion of n^2. %H A086015 G. C. Greubel, <a href="/A086015/b086015.txt">Table of n, a(n) for n = 0..1000</a> %t A086015 DigitCount[(Range[0, 100])^2, 10, 7] (* _G. C. Greubel_, Dec 13 2016 *) %o A086015 (PARI) A086015(n)=#select(d->d==7,digits(n^2)) \\ _M. F. Hasler_, Feb 21 2016 %Y A086015 Cf. 0's A086008, 1's A086009, 2's A086010, 3's A086011, 4's A086012, 5's A086013, 6's A086014, 8's A086016, 9's A086017. %Y A086015 Cf. A269247 for the n^3 analog. %K A086015 base,nonn %O A086015 0,77 %A A086015 _Jason Earls_, Jul 07 2003