OFFSET
0,4
FORMULA
E.g.f.: (sec(x)+tan(x))*(exp(x)-exp(-2*x))/3.
a(n) ~ n! * (exp(3*Pi/2)-1) * 2^(n+2) / (3 * exp(Pi) * Pi^(n+1)). - Vaclav Kotesovec, Jun 12 2015
PROG
(Python)
from itertools import accumulate, islice
def A101474_gen(): # generator of terms
blist, a, b = tuple(), 0, -1
while True:
yield (blist := tuple(accumulate(reversed(blist), initial=a)))[-1]
a, b = -b, -2*a-b
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Jan 21 2005
STATUS
approved