A127065 a(n) = n! - (n-2)^2.

0, 2, 5, 20, 111, 704, 5015, 40284, 362831, 3628736, 39916719, 479001500, 6227020679, 87178291056, 1307674367831, 20922789887804, 355687428095775, 6402373705727744, 121645100408831711, 2432902008176639676

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..445

Formula

(-23*n+116)*a(n) + (23*n^2-91*n-74)*a(n-1) + (-25*n^2+97*n-53)*a(n-2) + (n-2)*(2*n-21)*a(n-3) = 0. - R. J. Mathar, Sep 30 2013

E.g.f.: (4-3*x - (4-7*x+4*x^2-x^3)*exp(x))/(1-x). - G. C. Greubel, Aug 11 2019

Maple

seq(n! - (n-2)^2, n=1..25); # G. C. Greubel, Aug 11 2019

Mathematica

Table[(m!-(m-2)^2 ), {m, 25}]

Prog

(PARI) vector(25, n, n! - (n-2)^2) \\ G. C. Greubel, Aug 11 2019
(Magma) [Factorial(n) - (n-2)^2: n in [1..25]]; // G. C. Greubel, Aug 11 2019
(Sage) [factorial(n) - (n-2)^2 for n in (1..25)] # G. C. Greubel, Aug 11 2019
(GAP) List([1..25], n-> Factorial(n) -(n-2)^2); # G. C. Greubel, Aug 11 2019

Crossrefs

Sequence in context: A305922 A019536 A129949 * A168357 A052850 A000130

Adjacent sequences: A127062 A127063 A127064 * A127066 A127067 A127068

Keyword

easy,nonn

Author

Zerinvary Lajos, Mar 21 2007

Status

approved