A225846 Denominator of c(n) = 2^(2*n)*(2^(2*n) - 1)/(2*n)!, a coefficient used in the expansion of tan(x) as Sum_{n>=1} c(n)*|Bernoulli(2*n)|*x^(2*n-1).

1, 1, 1, 5, 21, 4725, 1485, 14189175, 42567525, 516891375, 11249435925, 714620417135625, 2124921731625, 16025362854266390625, 605758715891269565625, 5703572324950265390625, 480509193164339417203125, 22913080876041525109331015625, 92765509619601316232109375

Offset: 0

Author

Jean-François Alcover, May 17 2013

Keywords

• nonn
• frac
• easy

References

• George Boros and Victor H. Moll, Irresistible integrals, Cambridge University Press (2006), p. 63.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..250

Crossrefs

Cf. A225845 (numerators), A000367, A002445, A002430, A036279.

Programs

Magma

[Denominator(2^(2*n)*(2^(2*n)-1)/Factorial(2*n)): n in [0..20]]; // Vincenzo Librandi, Jul 17 2013

Mathematica

Table[2^(2*n)*(2^(2*n)-1)/(2*n)! // Denominator, {n, 0, 20}]