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A059968 Number of 10-ary trees.

%I A059968 #56 Jul 02 2025 16:02:01
%S A059968 1,1,10,145,2470,46060,910252,18730855,397089550,8612835715,
%T A059968 190223180840,4263421511271,96723482198980,2216905597676000,
%U A059968 51256802757808320,1194060413809070710,27999654303202465310,660370070571422998410,15654733143626084944150
%N A059968 Number of 10-ary trees.
%C A059968 From _Wolfdieter Lang_, Feb 06 2020: (Start)
%C A059968 Ninth column of triangle A062993 (without leading zeros). A Pfaff-Fuss or 10-Raney sequence.
%C A059968 a(n), n>=1, enumerates 10-ary trees (rooted, ordered, incomplete) with n vertices (including the root).
%C A059968 See Graham et al., Hilton and Pedersen, Hoggat and Bicknell, Frey and Sellers references given in A062993. (End)
%C A059968 This is instance k = 10 of the generalized Catalan family {C(k, n)}_{n>=0} given in a comment of A130564 - _Wolfdieter Lang_, Feb 05 2024
%D A059968 G. Pólya and G. Szegő, Problems and Theorems in Analysis, Springer-Verlag, Heidelberg, New York, 2 vols., 1972, Vol. 1, problem 211, p. 146 with solution on p. 348.
%H A059968 S. Heubach, N. Y. Li and T. Mansour, <a href="https://doi.org/10.1016/j.disc.2007.11.012">Staircase tilings and k-Catalan structures</a>, Discrete Math., 308 (2008), 5954-5964.
%F A059968 G.f. A(x) satisfies: A = x + A^10.
%F A059968 a(n) = binomial(k*n, n)/((k-1)*n+1), for k=10.
%F A059968 Recurrence: a(0) = 1; a(n) = Sum_{i1+i2+..i10=n-1} a(i1)*a(i2)*...*a(i10) for n>=1. - _Robert FERREOL_, Apr 01 2015
%F A059968 From _Wolfdieter Lang_, Feb 06 2020: (Start)
%F A059968 a(n) = A062993(n+8, 8). [Corrected by _Robert FERREOL_, Apr 01 2015]
%F A059968 G.f.: RootOf((_Z^10)*x-_Z+1) (Maple notation, from ECS, see links for A007556).
%F A059968 G.f.: hypergeometric([1, 2, 3, 4, 5, 6, 7, 8, 9]/10, [2, 3, 4, 5, 6, 7, 8, 10]/9, (10^10/9^9)*x),
%F A059968 E.g.f.: hypergeometric([1, 2, 3, 4, 5, 6, 7, 8, 9]/10, [2, 3, 4, 5, 6, 7, 8, 9, 10]/9, (10^10/9^9)*x).
%F A059968 For other family members see the crossreferences.
%F A059968 (End)
%F A059968 D-finite with recurrence 81*n*(9*n-7)*(9*n-5)*(3*n-1)*(9*n-1)*(9*n+1)*(3*n-2)*(9*n-4)*(9*n-2)*a(n) -800*(10*n-9)*(5*n-4)*(10*n-7)*(5*n-3)*(2*n-1)*(5*n-2)*(10*n-3)*(5*n-1)*(10*n-1)*a(n-1)=0. - _R. J. Mathar_, Mar 21 2022
%F A059968 a(n) ~ (10^10/9^9)^n*sqrt(10/(2*Pi*(9*n)^3)). - _Robert A. Russell_, Jul 15 2024
%F A059968 G.f. A(x) satisfies A(x) = 1/A(-x*A(x)^19). - _Seiichi Manyama_, Jun 16 2025
%e A059968 There are a(2)=10 10-ary trees (vertex degree <=10 and 10 possible branchings) with 2 vertices (one of them the root). Adding one more branch (one more vertex) to these 10 trees yields 10*10+binomial(10,2)=145=a(3) such trees. - _Wolfdieter Lang_, Sep 14 2007.
%p A059968 seq(binomial(10*k+1, k)/(9*k+1), k=0..30);
%p A059968 n:=30:G:=series(RootOf(g = 1+x*g^10, g), x=0, n+1):seq(coeff(G, x, k), k=0..n); # _Robert FERREOL_, Apr 01 2015
%t A059968 a[n_] := Binomial[10n, n]/(9n+1);
%t A059968 a /@ Range[0, 25] (* _Jean-François Alcover_, Jan 17 2020 *)
%Y A059968 Related algebraic sequences concerning trees: strictly k-ary trees (A000108: s=x+s^2, A001263: s=(x, y)+(x, s)+(s, y)+(s, s))), (A001764: s=x+s^3), (A002293: s=x+s^4), (A002294: s=x+s^5), (A002295: s=x+s^6), (A002296: s=x+s^7), (A007556: s=x+s^8), at most k-ary trees (A001006: s=x+xs+xs^2), (A036765-A036769, s=x+xs^2....+xs^k, k=3, 4, 5, 6, 7).
%Y A059968 Pfaff-Fuss A062993 column members: A000108, A001764, A002293, A002294, A002295, A002296, A007556, A062994, A230388.
%Y A059968 Cf. A130564.
%K A059968 nonn,easy
%O A059968 0,3
%A A059968 Claude Lenormand (claude.lenormand(AT)free.fr), Mar 05 2001
%E A059968 More terms from _James Sellers_, Mar 15 2001
%E A059968 a(0)=1 inserted by _Alois P. Heinz_, Jan 17 2020
%E A059968 A062744 merged into this sequence by _Wolfdieter Lang_, Feb 06 2020