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 A359245 #14 Dec 23 2022 07:50:44
%S A359245 1,0,81,289,1089,8836,6889,80089,688900,1868689,8508889,29888089,
%T A359245 288898009,983888689,3808988089,8680089889,86908808809,488088068689,
%U A359245 878686888689,2888986888804,48890888808804,108506888888896,88869893888889,880881089888881,788088668888889
%N A359245 The smallest square with exactly n circular loops (or holes) in its decimal expansion (A064532).
%C A359245 The digit 8 has two loops, the digits 0, 6 and 9 have one loop, and other digits (including 4) have no hole.
%C A359245 Least square k such that A064532(k) = n.
%e A359245 a(3) = 289 because 8 has two loops and 9 has one loop for a total of 3, and 289 is the smallest such square.
%o A359245 (PARI) a(n) = { for (k=0, oo, my (d=digits(k^2)); if (n==(k==0)+sum(i=1, #d, [1, 0, 0, 0, 0, 0, 1, 0, 2, 1][1+d[i]]), return (k^2))) } \\ _Rémy Sigrist_, Dec 22 2022
%Y A359245 Cf. A064532.
%Y A359245 Similar: A331898 (primes), A337842 (palindromes).
%K A359245 nonn,base
%O A359245 0,3
%A A359245 _Bernard Schott_, Dec 22 2022
%E A359245 More terms from _Rémy Sigrist_, Dec 22 2022