OFFSET
0,3
COMMENTS
Boustrophedon transform of shifted factorial numbers.
FORMULA
a(n) ~ (n-1)! * (1 + sin(1)) / cos(1). - Vaclav Kotesovec, Aug 23 2021
MATHEMATICA
nmax = 22; CoefficientList[Series[-Log[1 - x] (Sec[x] + Tan[x]), {x, 0, nmax}], x] Range[0, nmax]!
t[n_, 0] := If[n == 0, 0, (n - 1)!]; t[n_, k_] := t[n, k] = t[n, k - 1] + t[n - 1, n - k]; a[n_] := t[n, n]; Table[a[n], {n, 0, 22}]
PROG
(Python)
from itertools import accumulate, count, islice
def A347072_gen(): # generator of terms
blist, m = (0, ), 1
yield from blist
for i in count(1):
yield (blist := tuple(accumulate(reversed(blist), initial=m)))[-1]
m *= i
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Aug 15 2021
STATUS
approved