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A183909 Number of nondecreasing arrangements of n+2 numbers in 0..6 with each number being the sum mod 7 of two others. 1
1, 1, 22, 136, 470, 1193, 2525, 4752, 8238, 13438, 20912, 31340, 45538, 64475, 89291, 121316, 162090, 213384, 277222, 355904, 452030, 568525, 708665, 876104, 1074902, 1309554, 1585020, 1906756, 2280746, 2713535, 3212263, 3784700, 4439282, 5185148 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Column 6 of A183912.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..76

FORMULA

Empirical: a(n) = (1/720)*n^6 + (11/240)*n^5 + (89/144)*n^4 + (209/48)*n^3 - (13003/360)*n^2 + (531/10)*n + 12 for n>3.

Conjectures from Colin Barker, Apr 06 2018: (Start)

G.f.: x*(1 - 6*x + 36*x^2 - 32*x^3 - 20*x^4 + 3*x^5 + 40*x^6 - 16*x^7 - 9*x^8 + 4*x^9) / (1 - x)^7.

a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>10.

(End)

EXAMPLE

All solutions for n=2:

..0

..0

..0

..0

CROSSREFS

Cf. A183912.

Sequence in context: A254698 A041936 A254699 * A263481 A238170 A275799

Adjacent sequences:  A183906 A183907 A183908 * A183910 A183911 A183912

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 07 2011

STATUS

approved

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Last modified October 15 18:22 EDT 2019. Contains 328037 sequences. (Running on oeis4.)