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A051181 Number of 4-element intersecting families of an n-element set. 10
0, 0, 0, 4, 365, 11770, 278455, 5715094, 108498285, 1963243930, 34404675635, 589459538734, 9933916068505, 165358097339890, 2726894329246815, 44648990949187174 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

REFERENCES

V. Jovovic, G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, Diskretnaya Matematika, 11 (1999), no. 4, 127-138 (translated in Discrete Mathematics and Applications, 9, (1999), no. 6).

LINKS

Table of n, a(n) for n=0..15.

Index entries for linear recurrences with constant coefficients, signature (83, -3052, 65670, -919413, 8804499, -58966886, 277278100, -904270136, 1982352768, -2749917312, 2142305280, -696729600).

FORMULA

a(n) = 1/4!(16^n-6*12^n+12*10^n-9^n-22*8^n+15*7^n+12*6^n-17*5^n+17*4^n-11*3^n-6*2^n+6).

G.f.: -x^3*(64667520*x^8 -81966960*x^7 +42070268*x^6 -11421992*x^5 +1766529*x^4 -152845*x^3 +6317*x^2 -33*x -4)/((x-1)*(2*x-1)*(3*x-1)*(4*x-1)*(5*x-1)*(6*x-1)*(7*x-1)*(8*x-1)*(9*x-1)*(10*x-1)*(12*x-1)*(16*x-1)). [Colin Barker, Jul 30 2012]

CROSSREFS

Cf. A036239, A051180-A051185.

Sequence in context: A051955 A177114 A109760 * A154682 A154569 A038015

Adjacent sequences:  A051178 A051179 A051180 * A051182 A051183 A051184

KEYWORD

nonn,easy

AUTHOR

Vladeta Jovovic, Goran Kilibarda

STATUS

approved

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Last modified May 22 15:30 EDT 2017. Contains 286876 sequences.