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A167060
Number of spanning trees in G X P_n, where G = {{1, 2}, {1, 3}, {1, 4}, {1, 5}, {2, 3}, {2, 4}, {2, 5}}
1
20, 15680, 10368000, 6788875520, 4442379540500, 2906788405248000, 1901996646002328980, 1244531724569497441280, 814333290473214499968000, 532841946954369840453512000, 348653977101113682528774921620, 228134433564164121977905348608000, 149274992387437573877742622270584980
OFFSET
1,1
REFERENCES
F. Faase, On the number of specific spanning subgraphs of the graphs A X P_n, Ars Combin. 49 (1998), 129-154.
FORMULA
a(n) = 720 a(n-1)
- 43920 a(n-2)
+ 624783 a(n-3)
- 2247840 a(n-4)
+ 2247840 a(n-5)
- 624783 a(n-6)
+ 43920 a(n-7)
- 720 a(n-8)
+ a(n-9)
G.f.: -20x(x^7 +64x^6 -2160x^5 +4273x^4 +4273x^3 -2160x^2 +64x +1)/ (x^9 -720x^8 +43920x^7 -624783x^6 +2247840x^5 -2247840x^4 +624783x^3 -43920x^2 +720x -1).
CROSSREFS
Sequence in context: A173790 A028667 A201507 * A172661 A172758 A146497
KEYWORD
nonn
AUTHOR
STATUS
approved