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A183956
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Number of strings of numbers x(i=1..5) in 0..n with sum i^2*x(i) equal to n*25.
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1
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2, 5, 10, 27, 53, 94, 161, 259, 399, 578, 811, 1120, 1505, 1985, 2562, 3267, 4104, 5092, 6249, 7595, 9146, 10923, 12948, 15245, 17831, 20735, 23980, 27592, 31597, 36020, 40894, 46252, 52114, 58520, 65494, 73076, 81300, 90195, 99807, 110163, 121306
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n)=a(n-1)+a(n-4)-a(n-5)+a(n-9)-a(n-10)-a(n-13)+a(n-14)+a(n-16)-a(n-17)-a(n-20)+a(n-21)-a(n-34)+a(n-35)+a(n-38)-a(n-39)-a(n-41)+a(n-42)+a(n-45)-a(n-46)+a(n-50)-a(n-51)-a(n-54)+a(n-55)
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EXAMPLE
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All solutions for n=3
..0....1....1....0....1....2....3....3....0....0
..0....2....2....0....2....0....1....1....0....0
..2....2....0....0....1....0....3....2....3....1
..2....3....1....0....2....3....1....0....3....1
..1....0....2....3....1....1....1....2....0....2
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MATHEMATICA
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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[5, n];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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