A171107 - OEIS

%I #22 Dec 14 2018 09:19:39

%S 1,2,21,552,27385,2205840,262793181,43462178816,9531675497457,

%T 2677576265015040,937689127821286885,400556244184058840064,

%U 205018515960316713766761,123868925489567035630641152,87231398219233211815174239405,70827813121227086927005549854720,65683870009665683776967740707164641

%N a(n) = n*A171106(n).

%H Gheorghe Coserea, <a href="/A171107/b171107.txt">Table of n, a(n) for n = 1..222</a>

%H Sergey Fomin and Grigory Mikhalkin, <a href="http://arxiv.org/abs/0906.3828">Labeled floor diagrams for plane curves</a>, arXiv:0906.3828 [math.AG], 2009-2010.

%F Sergey Fomin and Grigory Mikhalkin give a recurrence.

%t terms = 17; Clear[b]; b[1] = b[2] = 1;

%t y[x_] = Sum[d^2 b[d] x^d/(2 d)!, {d, 1, terms+1}];

%t f = x (4 y'[x] - E^y[x] - x E^y[x] y'[x]) - 2 y[x] + O[x]^(terms + 1);

%t Solve[0 == Thread[CoefficientList[f, x]]][[1]] /. Rule -> Set;

%t a[n_] := n b[n];

%t Array[a, terms] (* _Jean-François Alcover_, Dec 14 2018 *)

%Y Cf. A171106.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Sep 27 2010

%E Terms a(15) and beyond from _Gheorghe Coserea_, Jan 02 2018