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 A068240 1/2 the number of colorings of a 4 X 4 square array with n colors. 2
 1, 3906, 3000366, 414425080, 19064362455, 428429377026, 5861180425996, 55823546748096, 403783634784285, 2353615149832210, 11531349080992026, 48981767072238936, 184656623163700051, 629125059062885490, 1964980839044519640, 5691311662142685376 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 LINKS Alois P. Heinz, Table of n, a(n) for n = 2..1000 FORMULA From Alois P. Heinz, Apr 27 2012 (Start) G.f.: -(2507986*x^14 +349887529*x^13 +12282125725*x^12 +158263444274*x^11 +896159384816*x^10 +2455337616143*x^9 +3417678462327*x^8 +2453922059100*x^7 +895941969162*x^6 +158666067383*x^5 +12424532171*x^4 +363949394*x^3 +2934100*x^2 +3889*x+1)*x^2 / (x-1)^17. a(n) = n*(n-1)*(n^14 -23*n^13 +253*n^12 -1762*n^11 +8675*n^10 -31939*n^9 +90723*n^8 -202160*n^7 +355622*n^6 -492434*n^5 +529770*n^4 -430857*n^3 +251492*n^2 -94782*n +17493)/2. (End) MAPLE a:= n-> n*(n-1)*(17493+(-94782+(251492+(-430857+(529770+(-492434 +(355622+(-202160+(90723+(-31939+(8675+(-1762+(253 +(-23+n)*n)*n) *n)*n)*n)*n) *n)*n) *n)*n) *n)*n)*n) /2: seq(a(n), n=2..30); # Alois P. Heinz, Apr 27 2012 CROSSREFS Cf. A068239-A068305, A000332, A002417, A027441, A182368, A182406. Sequence in context: A115468 A066386 A326385 * A022212 A131409 A209732 Adjacent sequences:  A068237 A068238 A068239 * A068241 A068242 A068243 KEYWORD nonn AUTHOR R. H. Hardin, Feb 24 2002 STATUS approved

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Last modified April 5 12:20 EDT 2020. Contains 333241 sequences. (Running on oeis4.)