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A257857
Sequentially filled binary triangle rotated 180 degrees and then superimposed and added to the original triangle.
1
2, 1, 1, 0, 2, 0, 1, 1, 1, 1, 2, 0, 2, 0, 2, 1, 1, 1, 1, 1, 1, 0, 2, 0, 2, 0, 2, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 0, 2, 0, 2, 0, 2, 0, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 0, 2, 0, 2
OFFSET
1,1
COMMENTS
The integers in the LINKS illustration hang like ornaments on a tree.
FORMULA
T(n,k)=1 if n even, 1<=k<=n.
T(n,k)=2 if n odd and (n+1)/2+k even, 1<=k<=n.
T(n,k)=0 if n odd and (n+1)/2+k odd, 1<=k<=n.
EXAMPLE
Triangle T(n,k) begins: Row sums
2; 2
1, 1; 2
0, 2, 0; 2
1, 1, 1, 1; 4
2, 0, 2, 0, 2; 6
1, 1, 1, 1, 1, 1; 6
0, 2, 0, 2, 0, 2, 0; 6
1, 1, 1, 1, 1, 1, 1, 1; 8
MAPLE
A257857 := proc(n, k)
if type(n, 'even') then
1 ;
elif type((n+1)/2+k, 'even') then
2 ;
else
0;
end if;
end proc:
CROSSREFS
For row sums for the three other variations of this build process, see A186421, A201629, A240828.
Sequence in context: A180997 A143439 A105469 * A339871 A276806 A308427
KEYWORD
nonn,tabl,easy
AUTHOR
Craig Knecht, Jul 12 2015
STATUS
approved