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 A183948 #12 Jun 02 2025 03:23:05 %S A183948 1,2,3,8,27,78,219,649,1805,4987,13179,34331,87203,217281,532073, %T A183948 1278041,3025466,7046194,16192534,36706373,82197783,181900279, %U A183948 398099637,862217855,1848842707,3927404946,8267742253,17257223344,35726693834 %N A183948 Number of strings of numbers x(i=1..n) in 0..4 with sum i^2*x(i) equal to n^2*4. %C A183948 Column 4 of A183953 %H A183948 R. H. Hardin, <a href="/A183948/b183948.txt">Table of n, a(n) for n = 1..60</a> %e A183948 Some solutions for n=6 %e A183948 ..0....4....2....3....4....0....3....2....2....0....4....0....2....3....4....2 %e A183948 ..2....1....2....3....4....3....0....1....4....2....1....3....1....4....1....1 %e A183948 ..2....2....1....2....3....0....1....0....2....1....1....1....1....0....4....4 %e A183948 ..2....2....4....0....0....2....2....1....0....1....1....3....2....4....4....1 %e A183948 ..2....2....1....3....1....4....4....2....0....3....3....3....1....1....0....2 %e A183948 ..1....1....1....1....2....0....0....2....3....1....1....0....2....1....1....1 %t A183948 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 A183948 T[n_, k_] := r[n, k, k*n^2]; %t A183948 a[n_] := T[n, 4]; %t A183948 Table[a[n], {n, 1, 40}] (* _Jean-François Alcover_, Jul 22 2022, after _R. J. Mathar_ in A183953 *) %K A183948 nonn %O A183948 1,2 %A A183948 _R. H. Hardin_, Jan 08 2011