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A180183 Triangle read by rows: T(n,k) is the number of compositions of n without 8's and having k parts; 1 <= k <= n. 6
1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 6, 4, 1, 1, 5, 10, 10, 5, 1, 1, 6, 15, 20, 15, 6, 1, 0, 7, 21, 35, 35, 21, 7, 1, 1, 6, 28, 56, 70, 56, 28, 8, 1, 1, 7, 33, 84, 126, 126, 84, 36, 9, 1, 1, 8, 39, 116, 210, 252, 210, 120, 45, 10, 1, 1, 9, 46, 153, 325, 462, 462, 330, 165, 55, 11, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,5

REFERENCES

P. Chinn and S. Heubach, Compositions of n with no occurrence of k, Congressus Numerantium, 164 (2003), pp. 33-51.

R.P. Grimaldi, Compositions without the summand 1, Congressus Numerantium, 152, 2001, 33-43.

LINKS

Table of n, a(n) for n=1..78.

P. Chinn and S. Heubach, Integer Sequences Related to Compositions without 2's, J. Integer Seqs., Vol. 6, 2003.

FORMULA

Number of compositions of n without p's and having k parts = Sum_{j=(pk-n)/(p-1)..k} (-1)^(k-j)*binomial(k,j)*binomial(n-pk+pj-1, j-1).

For a given p, the g.f. of the number of compositions without p's is G(t,z) = t*g(z)/(1-t*g(z)), where g(z) = z/(1-z) - z^p; here z marks sum of parts and t marks number of parts.

EXAMPLE

T(10,2)=7 because we have (1,9),(9,1),(3,7),(7,3),(4,6),(6,4), and (5,5).

Triangle starts:

  1;

  1,  1;

  1,  2,  1;

  1,  3,  3,  1;

  1,  4,  6,  4,  1;

  1,  5, 10, 10,  5,  1;

  1,  6, 15, 20, 15,  6,  1;

  0,  7, 21, 35, 35, 21,  7,  1;

  1,  6, 28, 56, 70, 56, 28,  8,  1;

MAPLE

p:= 8: T := proc (n, k) options operator, arrow: sum((-1)^(k-j)*binomial(k, j)*binomial(n-p*k+p*j-1, j-1), j = (p*k-n)/(p-1) .. k) end proc: for n to 13 do seq(T(n, k), k = 1 .. n) end do; # yields sequence in triangular form

p := 8: g := z/(1-z)-z^p: G := t*g/(1-t*g): Gser := simplify(series(G, z = 0, 15)): for n to 13 do P[n] := sort(coeff(Gser, z, n)) end do: for n to 13 do seq(coeff(P[n], t, k), k = 1 .. n) end do; # yields sequence in triangular form

with(combinat): m := 8: T := proc (n, k) local ct, i: ct := 0: for i to numbcomp(n, k) do if member(m, composition(n, k)[i]) = false then ct := ct+1 else end if end do: ct end proc: for n to 12 do seq(T(n, k), k = 1 .. n) end do; # yields sequence in triangular form

MATHEMATICA

p = 8; max = 14; g = z/(1-z) - z^p; G = t*g/(1-t*g); Gser = Series[G, {z, 0, max+1}]; t[n_, k_] := SeriesCoefficient[Gser, {z, 0, n}, {t, 0, k}]; Table[t[n, k], {n, 1, max}, {k, 1, n}] // Flatten (* Jean-Fran├žois Alcover, Jan 28 2014, after Maple *)

CROSSREFS

Cf. A011973, A180177, A180178, A180179, A180180, A180181, A180182.

Sequence in context: A095144 A144398 A034932 * A273914 A094495 A154926

Adjacent sequences:  A180180 A180181 A180182 * A180184 A180185 A180186

KEYWORD

nonn,tabl

AUTHOR

Emeric Deutsch, Aug 15 2010

STATUS

approved

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Last modified June 5 11:52 EDT 2020. Contains 334840 sequences. (Running on oeis4.)