1,6

Number of surjections from an n-element set onto a six-element set, with n >= 6. - Mohamed Bouhamida (bhmd95(AT)yahoo.fr), Dec 15 2007

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).

H. T. Davis, Tables of the Mathematical Functions. Vols. 1 and 2, 2nd ed., 1963, Vol. 3 (with V. J. Fisher), 1962; Principia Press of Trinity Univ., San Antonio, TX, Vol. 2, p. 212.

J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 33.

J. F. Steffensen, Interpolation, 2nd ed., Chelsea, NY, 1950, see p. 54.

A. H. Voigt, Theorie der Zahlenreihen und der Reihengleichungen, Goschen, Leipzig, 1911, p. 31.

A. H. Voigt, Theorie der Zahlenreihen und der Reihengleichungen, Leipzig, 1911.

Sum((-1)^i*binomial(6, i)*(6-i)^n, i = 0 .. 5).

a(n)=6^n-C(6,5)*5^n+C(6,4)*4^n-C(6,3)*3^n+C(6,2)*2^n-C(6,1) with n>=6. - Mohamed Bouhamida (bhmd95(AT)yahoo.fr), Dec 15 2007

G.f.:(720*x^6)/((x-1)*(6*x-1)*(4*x-1)*(3*x-1)*(2*x-1)*(5*x-1)) [From Maksym Voznyy (voznyy(AT)mail.ru), Jul 26 2009]

720/(-1+z)/(6*z-1)/(4*z-1)/(3*z-1)/(2*z-1)/(5*z-1);

with (combstruct):ZL:=[S, {S=Sequence(U, card=r), U=Set(Z, card>=1)}, labeled]: seq(count(subs(r=6, ZL), size=m), m=1..22); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 09 2007

Cf. A001117, A000919, A019538, A000920.

Cf. A000918, A000919, A001117, A001118.

Sequence in context: A004033 A137891 A056271 this_sequence A052779 A037212 A126781

Adjacent sequences: A000917 A000918 A000919 this_sequence A000921 A000922 A000923

nonn

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

G.f. proposed by Maksym Voznyy checked and corrected by R. J. Mathar, Sep 16 2009.