OFFSET
1,13
LINKS
Andrew Howroyd, Antidiagonals n = 1..27, flattened
FORMULA
T(n,m)=0 for n odd and m even, T(1,n)=0 for n>1.
T(2,n)=T(n,1)=T(2*n,2)=1, T(3,2*n+1)=T(n+1,3)=2^n.
EXAMPLE
The start of the sequence as table:
* 1 0 0 0 0 0 0 0 0 ...
* 1 1 1 1 1 1 1 1 1 ...
* 1 0 2 0 4 0 8 0 16 ...
* 1 1 4 8 23 55 144 360 921 ...
* 1 0 8 0 86 0 948 0 10444 ...
* 1 1 16 47 397 1770 11658 59946 359962 ...
* 1 0 32 0 1584 0 88418 0 4999752 ...
* 1 1 64 264 6820 52387 909009 8934966 130373192 ...
* 1 0 128 0 28002 0 7503654 0 2087813834 ...
* ...
PROG
(Python)
# Using graphillion
from graphillion import GraphSet
import graphillion.tutorial as tl
def A271592(n, k):
if k == 1: return 1
universe = tl.grid(k - 1, n - 1)
GraphSet.set_universe(universe)
start, goal = 1, n
paths = GraphSet.paths(start, goal, is_hamilton=True)
return paths.len()
print([A271592(j + 1, i - j + 1) for i in range(12) for j in range(i + 1)]) # Seiichi Manyama, Mar 28 2020
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Andrew Howroyd, Apr 10 2016
STATUS
approved