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A184704 Number of strings of numbers x(i=1..4) in 0..n with sum i*x(i) equal to n*4. 1

%I #9 Apr 14 2018 13:11:29

%S 2,7,14,28,46,74,107,154,208,278,357,456,565,697,841,1011,1195,1408,

%T 1636,1897,2175,2488,2820,3191,3582,4015,4470,4970,5494,6066,6663,

%U 7312,7988,8718,9477,10294,11141,12049,12989,13993,15031,16136,17276,18487,19735

%N Number of strings of numbers x(i=1..4) in 0..n with sum i*x(i) equal to n*4.

%C Row 4 of A184703.

%H R. H. Hardin, <a href="/A184704/b184704.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = a(n-1) + a(n-2) - 2*a(n-5) + a(n-8) + a(n-9) - a(n-10).

%F Empirical g.f.: x*(2 + 5*x + 5*x^2 + 7*x^3 + 4*x^4 + 4*x^5 + x^6 + x^7 + x^8 - x^9) / ((1 - x)^4*(1 + x)^2*(1 + x^2)*(1 + x + x^2)). - _Colin Barker_, Apr 14 2018

%e All solutions for n=3:

%e ..0....3....3....1....2....2....2....2....1....1....3....0....0....0

%e ..1....0....3....0....1....3....0....2....2....1....1....2....0....3

%e ..2....3....1....1....0....0....2....2....1....3....1....0....0....2

%e ..1....0....0....2....2....1....1....0....1....0....1....2....3....0

%Y Cf. A184703.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 20 2011

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Last modified March 28 13:42 EDT 2024. Contains 371254 sequences. (Running on oeis4.)