OFFSET
0,2
COMMENTS
Terms that are repeated in A011971 are included only once. In other words, dropping the elements on the diagonal and reading by rows gives this sequence. [Joerg Arndt, May 31 2013]
LINKS
Chai Wah Wu, Rows n = 0..200, flattened
EXAMPLE
Triangle T(n, k) begins:
[0] 1;
[1] 2, 3;
[2] 5, 7, 10;
[3] 15, 20, 27, 37;
[4] 52, 67, 87, 114, 151;
[5] 203, 255, 322, 409, 523, 674;
[6] 877, 1080, 1335, 1657, 2066, 2589, 3263;
...
MAPLE
T := (n, k) -> local i; add(binomial(k, i)*combinat:-bell(n - k + i + 1), i = 0..k): seq(seq(T(n, k), k=0..n), n = 0..9); # Peter Luschny, Dec 02 2023
MATHEMATICA
T[n_, k_] := Sum[Binomial[k, i] BellB[n - k + i + 1], {i, 0, k}];
Table[T[n, k], {n, 0, 8}, {k, 0, n}] // Flatten (* Jean-François Alcover, Nov 19 2019 *)
PROG
(Python)
from itertools import accumulate
A011972_list = blist = [1]
for _ in range(10**2):
b = blist[-1]
blist = list(accumulate([b]+blist))
A011972_list += blist[1:]
# Chai Wah Wu, Sep 02 2014, updated Chai Wah Wu, Sep 20 2014
CROSSREFS
KEYWORD
AUTHOR
STATUS
approved