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 A183947 #12 Jun 02 2025 03:22:58
%S A183947 1,1,2,4,10,26,61,147,339,771,1721,3770,8123,17233,36041,74322,151368,
%T A183947 304614,606305,1194266,2329462,4501905,8624652,16386814,30891283,
%U A183947 57801169,107387377,198165046,363321016,662012254,1199130676,2159720707
%N A183947 Number of strings of numbers x(i=1..n) in 0..3 with sum i^2*x(i) equal to n^2*3.
%C A183947 Column 3 of A183953
%H A183947 R. H. Hardin, <a href="/A183947/b183947.txt">Table of n, a(n) for n = 1..75</a>
%e A183947 All solutions for n=4
%e A183947 ..3....2....1....0
%e A183947 ..1....3....1....0
%e A183947 ..1....2....3....0
%e A183947 ..2....1....1....3
%t A183947 r[n_, k_, s_] := r[n, k, s] = Which[s < 0, 0, n == 0, If[s == 0, 1, 0], True, Sum[r[n - 1, k, s - c*n^2], {c, 0, k}]];
%t A183947 T[n_, k_] := r[n, k, k*n^2];
%t A183947 a[n_] := T[n, 3];
%t A183947 Table[a[n], {n, 1, 40}] (* _Jean-François Alcover_, Jul 22 2022, after _R. J. Mathar_ in A183953 *)
%K A183947 nonn
%O A183947 1,3
%A A183947 _R. H. Hardin_, Jan 08 2011