OFFSET
0,3
COMMENTS
Binomial transform of A101474.
FORMULA
E.g.f.: (sec(x) + tan(x))*(exp(2*x) - exp(-x))/3.
a(n) ~ n! * 2^(n+2) * (exp(Pi) - exp(-Pi/2)) / (3 * Pi^(n+1)). - Vaclav Kotesovec, Jun 12 2015
PROG
(Python)
from itertools import accumulate, islice
def A101473_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