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A183948
Number of strings of numbers x(i=1..n) in 0..4 with sum i^2*x(i) equal to n^2*4
1
1, 2, 3, 8, 27, 78, 219, 649, 1805, 4987, 13179, 34331, 87203, 217281, 532073, 1278041, 3025466, 7046194, 16192534, 36706373, 82197783, 181900279, 398099637, 862217855, 1848842707, 3927404946, 8267742253, 17257223344, 35726693834
OFFSET
1,2
COMMENTS
Column 4 of A183953
LINKS
EXAMPLE
Some solutions for n=6
..0....4....2....3....4....0....3....2....2....0....4....0....2....3....4....2
..2....1....2....3....4....3....0....1....4....2....1....3....1....4....1....1
..2....2....1....2....3....0....1....0....2....1....1....1....1....0....4....4
..2....2....4....0....0....2....2....1....0....1....1....3....2....4....4....1
..2....2....1....3....1....4....4....2....0....3....3....3....1....1....0....2
..1....1....1....1....2....0....0....2....3....1....1....0....2....1....1....1
MATHEMATICA
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[n_, k_] := r[n, k, k*n^2];
a[n_] := T[n, 4];
Table[a[n], {n, 1, 40}] (* Jean-François Alcover, Jul 22 2022, after R. J. Mathar in A183953 *)
CROSSREFS
Sequence in context: A246446 A296093 A041399 * A041503 A086613 A121401
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 08 2011
STATUS
approved