A280776 Numerators of coefficients in asymptotic expansion of C_n (number of connected chord diagrams, A000699).

1, -5, -43, -579, -44477, -5326191, -180306541, -203331297947, -58726239094693, -781618285277957, -1025587838964854273, -35763822710356866613, -330773478104531041960421, -237504847171108896327033959, -196526060612842999084524774697, -20633624138373135772483762873819

Offset: 0

Author

N. J. A. Sloane, Jan 19 2017

Keywords

• sign
• frac

Examples

			Coefficients are 1, -5/2, -43/8, -579/16, -44477/128, -5326191/1280, -180306541/3072, ...
		

Links

• Gheorghe Coserea, Table of n, a(n) for n = 0..101
• Michael Borinsky, Generating asymptotics for factorially divergent sequences, arXiv preprint arXiv:1603.01236 [math.CO], 2016.

Crossrefs

Cf. A000699, A280775, A111111, A280777, A280778, A280779, A280780, A280781.

Programs

PARI

A000699_seq(N) = {
  my(a = vector(N)); a[1] = 1;
  for (n=2, N, a[n] = sum(k=1, n-1, (2*k-1)*a[k]*a[n-k])); a;
};
seq(N) = my(C = 'x*Ser(A000699_seq(N))); Vec(x*exp(1-(2*C+C^2)/(2*x))/C);
apply(numerator, seq(16))  \\ Gheorghe Coserea, Jan 22 2017

Extensions

More terms from Gheorghe Coserea, Jan 22 2017