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A171107
a(n) = n*A171106(n).
2
1, 2, 21, 552, 27385, 2205840, 262793181, 43462178816, 9531675497457, 2677576265015040, 937689127821286885, 400556244184058840064, 205018515960316713766761, 123868925489567035630641152, 87231398219233211815174239405, 70827813121227086927005549854720, 65683870009665683776967740707164641
OFFSET
1,2
LINKS
Sergey Fomin and Grigory Mikhalkin, Labeled floor diagrams for plane curves, arXiv:0906.3828 [math.AG], 2009-2010.
FORMULA
Sergey Fomin and Grigory Mikhalkin give a recurrence.
MATHEMATICA
terms = 17; Clear[b]; b[1] = b[2] = 1;
y[x_] = Sum[d^2 b[d] x^d/(2 d)!, {d, 1, terms+1}];
f = x (4 y'[x] - E^y[x] - x E^y[x] y'[x]) - 2 y[x] + O[x]^(terms + 1);
Solve[0 == Thread[CoefficientList[f, x]]][[1]] /. Rule -> Set;
a[n_] := n b[n];
Array[a, terms] (* Jean-François Alcover, Dec 14 2018 *)
CROSSREFS
Cf. A171106.
Sequence in context: A158886 A092957 A356481 * A218768 A195736 A320653
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 27 2010
EXTENSIONS
Terms a(15) and beyond from Gheorghe Coserea, Jan 02 2018
STATUS
approved