0,3

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

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

A. Cayley, Calculation of the minimum N.G.F. of the binary seventhic, Collected Mathematical Papers. Vols. 1-13, Cambridge Univ. Press, London, 1889-1897, Vol. 10, p. 408-419.

H. Gupta et al., Tables of Partitions. Royal Society Mathematical Tables, Vol. 4, Cambridge Univ. Press, 1958, p. 2.

T. D. Noe, Table of n, a(n) for n=0..1000

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 355

a(n)=1+(a(n-2)+a(n-3)+a(n-4))-(2*a(n-7)+2*a(n-8)+a(n-9))+(a(n-11)+2*a(n-12)+2*a(n-13))- (a(n-16)+a(n-17)+a(n-18))+(a(n-20)) - Norman J. Meluch (norm(AT)iss.gm.com), Mar 09 2000

with(combstruct):ZL7:=[S, {S=Set(Cycle(Z, card<7))}, unlabeled]: seq(count(ZL7, size=n), n=0..50); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 24 2007

(Maple) a := n -> (Matrix(21, (i, j)-> if (i=j-1) then 1 elif j=1 then [1, 1, 0, 0, -1, 0, -2, 0, 1, 1, 1, 1, 0, -2, 0, -1, 0, 0, 1, 1, -1][i] else 0 fi)^n)[1, 1]; seq (a(n), n=0..50); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Jul 31 2008]

B:=[S, {S = Set(Sequence(Z, 1 <= card), card <=6)}, unlabelled]: seq(combstruct[count](B, size=n), n=0..50); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 21 2009]

CoefficientList[ Series[ 1/((1 - x)*(1 - x^2)*(1 - x^3)*(1 - x^4)*(1 - x^5)*(1 - x^6)), {x, 0, 60} ], x ]

Essentially same as A026812.

a(n)=A008284(n+6, 6), n >= 0.

Adjacent sequences: A001399 A001400 A001401 this_sequence A001403 A001404 A001405

Sequence in context: A036608 A136185 A026812 this_sequence A008629 A070289 A035961

nonn,easy

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