|
|
A306880
|
|
Expansion of e.g.f. (sec(x) + tan(x))/(1 + LambertW(-x)).
|
|
2
|
|
|
1, 2, 7, 44, 401, 4796, 70783, 1240448, 25146113, 578583952, 14892958551, 423979878816, 13225810908881, 448604790288448, 16437893908228367, 647074747622534912, 27233273311687115649, 1220273444664347994368, 57998633082360310382119, 2914426113026062106334720, 154378135436424206699590545
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
COMMENTS
|
Boustrophedon transform of A000312.
|
|
LINKS
|
|
|
FORMULA
|
|
|
MATHEMATICA
|
nmax = 20; CoefficientList[Series[(Sec[x] + Tan[x])/(1 + LambertW[-x]), {x, 0, nmax}], x] Range[0, nmax]!
t[n_, 0] := If[n < 1, 1, n^n]; t[n_, k_] := t[n, k] = t[n, k - 1] + t[n - 1, n - k]; a[n_] := t[n, n]; Array[a, 21, 0]
|
|
PROG
|
(Python)
from itertools import accumulate, count, islice
def A306880_gen(): # generator of terms
blist = tuple()
for i in count(0):
yield (blist := tuple(accumulate(reversed(blist), initial=i**i)))[-1]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|