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A003947 Coordination sequence for infinite tree with valency 5. +0
6
1, 5, 20, 80, 320, 1280, 5120, 20480, 81920, 327680, 1310720, 5242880, 20971520, 83886080, 335544320, 1342177280, 5368709120, 21474836480, 85899345920, 343597383680, 1374389534720, 5497558138880, 21990232555520 (list; graph; listen)
OFFSET

0,2

COMMENT

For n>=1, a(n+1) is equal to the number of functions f:{1,2,...,n+1}->{1,2,3,4,5} such that for fixed, different x_1, x_2,...,x_n in {1,2,...,n+1} and fixed y_1, y_2,...,y_n in {1,2,3,4,5} we have f(x_i)<>y_i, (i=1,2,...,n). - Milan R. Janjic (agnus(AT)blic.net), May 10 2007

LINKS

T. D. Noe, Table of n, a(n) for n=0..200

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 306

Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets

Index entries for sequences related to trees

FORMULA

Binomial transform of A060925. Its binomial transform is A003463 (without leading zero). - Paul Barry (pbarry(AT)wit.ie), May 19 2003

a(n)=(5*4^n-0^n)/4; G.f.: (1+x)/(1-4x); E.g.f.: (5exp(4x)-exp(0))/4. - Paul Barry (pbarry(AT)wit.ie), May 19 2003

a(n) = Sum_{ 0<=k<=n } A029653(n, k)*x^k for x = 3 . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jul 10 2005

a(n)=A146523(n)*A011782(n). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 08 2009]

MAPLE

k := 5; if n = 0 then 1 else k*(k-1)^(n-1); fi;

with(finance):seq(floor(futurevalue(5, 3, n)), n=-1..21); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 25 2009]

CROSSREFS

Sequence in context: A079820 A117422 A154639 this_sequence A033131 A022021 A165203

Adjacent sequences: A003944 A003945 A003946 this_sequence A003948 A003949 A003950

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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