A158455 a(n) = 2^(n-1)*(n-1)!*(4*n+1).

5, 18, 104, 816, 8064, 96000, 1336320, 21288960, 381911040, 7617576960, 167215104000, 4005730713600, 103985499340800, 2907670000435200, 87128076504268800, 2785241789890560000, 94612521108897792000, 3403308368004120576000, 129232476659005784064000

Offset: 1

Author

Karol A. Penson, Mar 19 2009

Keywords

• nonn

Comments

Exponential (EXP) transform of a(n) is A093620.

Programs

Magma

[2^(n-1)*Factorial(n-1)*(4*n+1): n in [1..25]]; // Vincenzo Librandi, Jul 06 2015

Mathematica

Table[2^(n-1)(n-1)!(4n+1),{n,30}] (* Harvey P. Dale, Sep 22 2011 *)

Formula

E.g.f.: Sum_{n>=1} a(n)*x^n/n! = 4*x/(1-2*x)-(1/2)*log(1-2*x).

Extensions

More terms from Harvey P. Dale, Sep 22 2011