OFFSET
0,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
FORMULA
a(n) ~ -2^(n-1/2) * n^(n-1) / exp(n-1/2). - Vaclav Kotesovec, Mar 29 2014
D-finite with recurrence: a(n) +2*(-n+1)*a(n-1) +2*(n-1)*a(n-2)=0. - R. J. Mathar, Jan 22 2020
MATHEMATICA
CoefficientList[Series[E^x*Sqrt[1-2*x], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Mar 29 2014 *)
PROG
(Sage)
def A055142(n):
@CachedFunction
def h(n):
return (-1)^n*2*(n-2)*abs(h(n-1)+h(n-2)) if n>1 else 1
return -(-1)^(n+1)*h(n+1)
[A055142(n) for n in (0..17)] # Peter Luschny, Nov 02 2012
CROSSREFS
KEYWORD
sign
AUTHOR
Christian G. Bower, May 09 2000
STATUS
approved