login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A051181
Number of 4-element intersecting families of an n-element set.
11
0, 0, 0, 4, 365, 11770, 278455, 5715094, 108498285, 1963243930, 34404675635, 589459538734, 9933916068505, 165358097339890, 2726894329246815, 44648990949187174, 727080119853611525, 11790570902483264650, 190587735542474633995, 3073193346666282232414
OFFSET
0,4
LINKS
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.
V. Jovovic, G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, (English translation), Discrete Mathematics and Applications, 9, (1999), no. 6.
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
MATHEMATICA
Table[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), {n, 0, 50}] (* G. C. Greubel, Oct 06 2017 *)
LinearRecurrence[{83, -3052, 65670, -919413, 8804499, -58966886, 277278100, -904270136, 1982352768, -2749917312, 2142305280, -696729600}, {0, 0, 0, 4, 365, 11770, 278455, 5715094, 108498285, 1963243930, 34404675635, 589459538734}, 20] (* Harvey P. Dale, Jul 04 2019 *)
PROG
(PARI) for(n=0, 25, print1((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. C. Greubel, Oct 06 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vladeta Jovovic, Goran Kilibarda
EXTENSIONS
More terms from Harvey P. Dale, Jul 04 2019
STATUS
approved