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 A213083 #16 Jun 30 2025 04:28:06
%S A213083 1,4,4,4,4,9,9,9,9,9,9,9,9,9,16,16,16,16,16,16,16,16,16,16,16,16,16,
%T A213083 16,16,16,25,25,25,25,25,25,25,25,25,25,25,25,25,25,25,25,25,25,25,25,
%U A213083 25,25,25,25,25,36,36,36,36,36,36,36,36,36,36,36,36,36
%N A213083 Each square n^2 appears n^2 number of times.
%F A213083 a(n) = A074279(n)^2. Alternatively, a(n) = (m+1)^2 if n > m(m+1)(2m+1)/6 and a(n) = m^2 otherwise where m = floor((3n)^(1/3)). - _Chai Wah Wu_, Jun 21 2025
%F A213083 Sum_{n>=1} (-1)^(n+1)/a(n) = A006752. - _Amiram Eldar_, Jun 30 2025
%t A213083 Flatten[Table[Table[n^2, {n^2}], {n, 6}]] (* _T. D. Noe_, Jun 05 2012 *)
%o A213083 (Python)
%o A213083 from sympy.core.intfunc import integer_nthroot
%o A213083 def A213083(n): return ((m:=integer_nthroot(3*n,3)[0])+(6*n>m*(m+1)*((m<<1)+1)))**2 # _Chai Wah Wu_, Jun 21 2025
%Y A213083 Cf. A000290, A006752, A074279.
%K A213083 nonn
%O A213083 1,2
%A A213083 _Jens Ahlström_, Jun 05 2012