A056116 - OEIS

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A056116

a(n) = 121*12^(n-2), a(0)=1, a(1)=10.

1, 10, 121, 1452, 17424, 209088, 2509056, 30108672, 361304064, 4335648768, 52027785216, 624333422592, 7492001071104, 89904012853248, 1078848154238976, 12946177850867712, 155354134210412544 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	COMMENTS	`For n>=2, a(n) is equal to the number of functions f:{1,2,...,n}->{1,2,3,4,5,6,7,8,9,10,11,12} such that for fixed, different x_1, x_2 in {1,2,...,n} and fixed y_1, y_2 in {1,2,3,4,5,6,7,8,9,10,11,12} we have f(x_1)<>y_1 and f(x_2)<> y_2. - Milan R. Janjic (agnus(AT)blic.net), Apr 19 2007` `a(n) is the number of generalized compositions of n when there are 11*i-1 different types of i, (i=1,2,...). [From Milan R. Janjic (agnus(AT)blic.net), Aug 26 2010]`
	REFERENCES	`A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pps. 194-196.`
	LINKS	`Vincenzo Librandi, Table of n, a(n) for n = 0..200` `Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets` `Index to sequences with linear recurrences with constant coefficients, signature (12).`
	FORMULA	`a(n) = 12a(n-1)+(-1)^nC(2, 2-n). G.f.: (1-x)^2/(1-12x).` `a(n) = Sum_{k, 0<=k<=n} A201780(n,k)10^k. - DELEHAM Philippe, Dec 05 2011`
	CROSSREFS	`Cf. A055996, A056002.` `Sequence in context: A202808 A091692 A098309 * A081784 A005174 A034668` `Adjacent sequences: A056113 A056114 A056115 * A056117 A056118 A056119`
	KEYWORD	`nonn,easy`
	AUTHOR	`Barry E. Williams, Jul 04 2000`
	EXTENSIONS	`More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jul 04 2000`

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Last modified February 13 16:05 EST 2012. Contains 205522 sequences.