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A000078 Tetranacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4) with a(0)=a(1)=a(2)=0, a(3)=1.
(Formerly M1108 N0423)
57

%I M1108 N0423

%S 0,0,0,1,1,2,4,8,15,29,56,108,208,401,773,1490,2872,5536,10671,20569,

%T 39648,76424,147312,283953,547337,1055026,2033628,3919944,7555935,

%U 14564533,28074040,54114452,104308960,201061985,387559437,747044834,1439975216,2775641472

%N Tetranacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4) with a(0)=a(1)=a(2)=0, a(3)=1.

%C a(n)=number of compositions of n-3 with no part greater than 4. Example: a(7)=8 because we have 1+1+1+1=2+1+1=1+2+1=3+1=1+1+2=2+2=1+3=4. - _Emeric Deutsch_, Mar 10 2004

%C In other words, a(n) is the number of ways of putting stamps in one row on an envelope using stamps of denominations 1, 2, 3 and 4 cents so as to total n-3 cents [Polya-Szego]. - _N. J. A. Sloane_, Jul 28 2012

%C a(n+4)=number of 0-1 sequences of length n that avoid 1111. - _David Callan_, Jul 19 2004

%C a(n)=number of matchings in the graph obtained by a zig-zag triangulation of a convex (n-3)-gon. Example: a(8)=15 because in the triangulation of the convex pentagon ABCDEA with diagonals AD and AC we have 15 matchings: the empty set, seven singletons and {AB,CD},{AB,DE},{BC,AD},{BC,DE},{BC,EA},{CD,EA} and {DE,AC}. - _Emeric Deutsch_, Dec 25 2004

%C Number of permutations satisfying -k<=p(i)-i<=r, i=1..n-3, with k=1, r=3. - _Vladimir Baltic_, Jan 17 2005

%D E. Deutsch, Problem 1613, Math. Mag., 75, No. 1, 64-64.

%D M. Feinberg, Fibonacci-Tribonacci, Fib. Quart. 1(#3) (1963), 71-74.

%D F. T. Howard and Curtis Cooper, Some identities for r-Fibonacci numbers, http://www.math-cs.ucmo.edu/~curtisc/articles/howardcooper/genfib4.pdf.

%D W. C. Lynch, The t-Fibonacci numbers and polyphase sorting, Fib. Quart., 8 (1970), pp. 6ff.

%D G. Pólya and G. Szegő, Problems and Theorems in Analysis, Springer-Verlag, NY, 2 vols., 1972, Vol. 1, p. 1, Problems 3 and 4.

%D Problem 2803, Amer. Math. Monthly, 33 (1926), 229-232.

%D J. Riordan, An Introduction to Combinatorial Analysis, Princeton University Press, Princeton, NJ, 1978.

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H T. D. Noe, <a href="/A000078/b000078.txt">Table of n, a(n) for n = 0..200</a>

%H Joerg Arndt, <a href="http://www.jjj.de/fxt/#fxtbook">Fxtbook</a>, pp.307-309

%H Vladimir Baltic, <a href="http://pefmath.etf.rs/vol4num1/AADM-Vol4-No1-119-135.pdf">On the number of certain types of strongly restricted permutations</a>, Applicable Analysis and Discrete Mathematics Vol. 4, No 1 (April, 2010), 119-135

%H P. J. Cameron, <a href="http://www.cs.uwaterloo.ca/journals/JIS/index.html">Sequences realized by oligomorphic permutation groups</a>, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.

%H INRIA Algorithms Project, <a href="http://algo.inria.fr/ecs/ecs?searchType=1&amp;service=Search&amp;searchTerms=11">Encyclopedia of Combinatorial Structures 11</a>

%H Tony D. Noe and Jonathan Vos Post, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL8/Noe/noe5.html">Primes in Fibonacci n-step and Lucas n-step Sequences,</a> J. of Integer Sequences, Vol. 8 (2005), Article 05.4.4

%H Simon Plouffe, <a href="http://www.lacim.uqam.ca/%7Eplouffe/articles/MasterThesis.pdf">Approximations de séries génératrices et quelques conjectures</a>, Dissertation, Université du Québec à Montréal, 1992.

%H Simon Plouffe, <a href="http://www.lacim.uqam.ca/%7Eplouffe/articles/FonctionsGeneratrices.pdf">1031 Generating Functions and Conjectures</a>, Université du Québec à Montréal, 1992.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Fibonaccin-StepNumber.html">Fibonacci n-Step Number.</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TetranacciNumber.html">Tetranacci Number.</a>

%H <a href="/index/Rea#recLCC">Index entries for sequences related to linear recurrences with constant coefficients</a>

%F a(n) =A001630(n)-a(n-1). - _Henry Bottomley_

%F G.f.: x^3/(1 - x - x^2 - x^3 - x^4).

%F G.f.: x^3 / (1 - x / (1 - x / (1 + x^3 / (1 + x / (1 - x / (1 + x)))))). - _Michael Somos_, May 12 2012

%F a(n) = term (1,4) in the 4x4 matrix [1,1,0,0; 1,0,1,0; 1,0,0,1; 1,0,0,0]^n. - _Alois P. Heinz_, Jun 12 2008

%F Another form of the g.f.: f(z)=(z^3-z^4)/(1-2*z+z^5) then a(n)=sum((-1)^i*binomial(n-3-4*i,i)*2^(n-3-5*i),i=0..floor((n-3)/5))-sum((-1)^i*binomial(n-4-4*i,i)*2^(n-4-5*i),i=0..floor((n-4)/5)) with natural convention sum(alpha(i),i=m..n)=0 for m>n. [_Richard Choulet_, Feb 22 2010]

%F a(n)=sum(k=1..n, sum(i=k..n mod(5*k-i,4)=0 binomial(k,(5*k-i)/4)*(-1)^((i-k)/4)*binomial(n-i+k-1,k-1))), n>0. [_Vladimir Kruchinin_, Aug 18 2010]

%F sum_{k=0..3*n} A000078(k+b)*A008287(n,k) = A000078(4*n+b), b>=0.

%F G.f.: x^3*(1 + x*(G(0)-1)/(x+1)) where G(k) = 1 + (1+x+x^2+x^3)/(1-x/(x+1/G(k+1) )); (recursively defined continued fraction). - _Sergei N. Gladkovskii_, Jan 26 2013

%F Starting (1, 2, 4, 8,...) = the INVERT transform of (1, 1, 1, 1, 0, 0, 0,...). [_Gary W. Adamson_, May 13 2013]

%e x^3 + x^4 + 2*x^5 + 4*x^6 + 8*x^7 + 15*x^8 + 29*x^9 + 56*x^10 + ...

%p A000078:=-1/(-1+z+z**2+z**3+z**4); [_Simon Plouffe_ in his 1992 dissertation.]

%p a:= n-> (<<1|1|0|0>, <1|0|1|0>, <1|0|0|1>, <1|0|0|0>>^n)[1, 4]: seq(a(n), n=0..50); # _Alois P. Heinz_, Jun 12 2008

%t CoefficientList[Series[x^3/(1 - x - x^2 - x^3 - x^4), {x, 0, 50}], x]

%t LinearRecurrence[{1, 1, 1, 1}, {0, 0, 0, 1}, 50] (* _Vladimir Joseph Stephan Orlovsky_, May 25 2011 *)

%o (PARI) {a(n) = if( n<0, 0, polcoeff( x^3 / (1 - x - x^2 - x^3 - x^4) + x * O(x^n), n))}

%o (Maxima) a(n):=sum(sum(if mod(5*k-i,4)>0 then 0 else binomial(k,(5*k-i)/4)*(-1)^((i-k)/4)*binomial(n-i+k-1,k-1),i,k,n),k,1,n); [_Vladimir Kruchinin_, Aug 18 2010]

%o (Haskell)

%o import Data.List (zipWith4)

%o a000078 n = a000078_list !! n

%o a000078_list = 0 : 0 : 0 : 1 : zipWith4 (\a b c d -> a + b + c + d)

%o a000078_list

%o (tail a000078_list)

%o (drop 2 a000078_list)

%o (drop 3 a000078_list) -- _Reinhard Zumkeller_, Apr 28 2011

%Y Row 4 of arrays A048887 and A092921 (k-generalized Fibonacci numbers).

%Y First differences are in A001631.

%K nonn,easy,nice

%O 0,6

%A _N. J. A. Sloane_.

%E More terms from _Henry Bottomley_, Oct 09 2000

%E Definition augmented (with 4 initial terms) by _Daniel Forgues_, Dec 02 2009

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Last modified April 24 10:30 EDT 2014. Contains 240983 sequences.