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A183907 Number of nondecreasing arrangements of n+2 numbers in 0..4 with each number being the sum mod 5 of two others. 1
1, 2, 20, 66, 148, 275, 457, 705, 1031, 1448, 1970, 2612, 3390, 4321, 5423, 6715, 8217, 9950, 11936, 14198, 16760, 19647, 22885, 26501, 30523, 34980, 39902, 45320, 51266, 57773, 64875, 72607, 81005, 90106, 99948, 110570, 122012, 134315, 147521, 161673 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Column 4 of A183912.
LINKS
FORMULA
Empirical: a(n) = (1/24)*n^4 + (3/4)*n^3 + (119/24)*n^2 - (95/4)*n + 23 for n>1.
Conjectures from Colin Barker, Apr 05 2018: (Start)
G.f.: x*(1 - 3*x + 20*x^2 - 24*x^3 + 3*x^4 + 4*x^5) / (1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>6.
(End)
EXAMPLE
All solutions for n=2:
..0....1
..0....2
..0....3
..0....4
CROSSREFS
Cf. A183912.
Sequence in context: A192351 A136905 A230644 * A216609 A226394 A287485
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 07 2011
STATUS
approved

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Last modified April 16 19:05 EDT 2024. Contains 371751 sequences. (Running on oeis4.)