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 A181675 #12 Feb 13 2021 04:31:32
%S A181675 3,41,1159,50049,2908411,212358985,18665359119,1917971421185,
%T A181675 225555471838387,29871434052884841,4398867465890529303,
%U A181675 712959801840558794625,126115813138335816685995
%N A181675 V(n,n^2), where V is the number of integer points in an n-dimensional sphere of Lee-radius n^2 centered at the origin.
%C A181675 Since V(n,d) is symmetric, we have V(n,n^2) = V(n^2,n).
%H A181675 Solomon W. Golomb and Lloyd R. Welch, <a href="https://www.jstor.org/stable/2099465">Perfect Codes in the Lee Metric and the Packing of Polyominoes</a>, SIAM Journal on Applied Mathematics Vol. 18, No. 2 (Mar. 1970), pp. 302-317.
%H A181675 Milan Janjić, <a href="https://arxiv.org/abs/1905.04465">On Restricted Ternary Words and Insets</a>, arXiv:1905.04465 [math.CO], 2019.
%F A181675 V(n,d) = Sum_{j=0..min(n,d)} 2^j * binomial(n,j)*binomial(d,j).
%F A181675 a(n) ~ exp(n-2) * (2*n)^(n - 3/2) / sqrt(Pi). - _Vaclav Kotesovec_, Feb 13 2021
%t A181675 Array[Sum[2^j*Binomial[#1, j] Binomial[#2, j], {j, 0, Min[#1, #2]}] & @@ {#, #^2} &, 13] (* _Michael De Vlieger_, Jul 05 2019 *)
%Y A181675 V(n, n) = A001850, V(n, 2n) = A026000 and V(n, 3n) = A026001.
%K A181675 easy,nonn
%O A181675 2,1
%A A181675 _Antonio Campello_, Nov 04 2010