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%I #23 Jun 13 2015 00:50:16
%S 1,6,49,392,3136,25088,200704,1605632,12845056,102760448,822083584,
%T 6576668672,52613349376,420906795008,3367254360064,26938034880512,
%U 215504279044096,1724034232352768,13792273858822144,110338190870577152
%N a(0)=1, a(1)=6, a(n)=49*8^(n-2) if n>=2.
%C For n>=2, a(n) is equal to the number of functions f:{1,2,...,n}->{1,2,3,4,5,6,7,8} such that for fixed, different x_1, x_2 in {1,2,...,n} and fixed y_1, y_2 in {1,2,3,4,5,6,7,8} we have f(x_1)<>y_1 and f(x_2)<> y_2. - _Milan Janjic_, Apr 19 2007
%C a(n) is the number of generalized compositions of n when there are 7*i-1 different types of i, (i=1,2,...). - _Milan Janjic_, Aug 26 2010
%D A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 194-196.
%H Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Enumerative Formulas for Some Functions on Finite Sets</a>
%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (8).
%F a(n) = 8*a(n-1) + (-1)^n*C(2, 2-n).
%F G.f.: (1-x)^2/(1-8*x).
%F a(n) = sum_{k, 0<=k<=n} A201780(n,k)*6^k. - _Philippe Deléham_, Dec 05 2011
%t Join[{1,6},NestList[8#&,49,20]] (* _Harvey P. Dale_, Dec 08 2013 *)
%Y First differences of A055274. Cf. A001018.
%K nonn,easy
%O 0,2
%A _Barry E. Williams_, Jun 03 2000
%E More terms from _James A. Sellers_, Jun 05 2000