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 A067479 #18 Mar 23 2021 05:39:23 %S A067479 9,0,900,9025,90000,900601,9000000,90003169,900000000,9000127161, %T A067479 90000000000,900001331856,9000000000000,90000000369889, %U A067479 900000000000000,9000000036988900,90000000000000000,900000001801523401 %N A067479 Smallest n-digit square starting with 9, or 0 if no such number exists. %F A067479 a(n+1) = (floor(sqrt(9*10^n)) + (n mod 2))^2, a(2)=0. - _Sascha Kurz_, Mar 18 2002 %F A067479 a(2k+1) = 9 * 10^(2k) for k >= 0. - _Bernard Schott_, Mar 23 2021 %o A067479 (PARI) a(n) = if (n==2, 0, (sqrtint(9*10^(n-1)) + (n-1) % 2)^2); \\ _Michel Marcus_, Mar 23 2021 %Y A067479 Cf. A000290, A035076 (roots), A045792. %Y A067479 Cf. 2: A067472, 3: A067473, 4: A067474, 5: A067475, 6: A067476, 7: A067477, 8: A067478. %K A067479 base,easy,nonn %O A067479 1,1 %A A067479 _Amarnath Murthy_, Feb 09 2002 %E A067479 More terms from _Sascha Kurz_, Mar 18 2002