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A106242
Same triangle as A106243, but with rows read in boustrophedon manner, i.e., in the order in which they were created.
3
1, 0, 1, 0, 1, 1, 0, 2, 3, 3, 0, 6, 11, 13, 13, 0, 26, 50, 67, 73, 73, 0, 146, 286, 403, 479, 505, 505, 0, 1010, 1994, 2876, 3565, 3997, 4143, 4143, 0, 8286, 16426, 23988, 30429, 35299, 38303, 39313, 39313, 0, 78626, 156242, 229844, 295572, 349989, 390403, 415115, 423401, 423401
OFFSET
0,8
LINKS
MAPLE
T:= proc(n, k) option remember;
local t;
if n<1 or k<1 then 0
elif n=1 and k=1 then 1
elif n=1 and irem(k, 2)=1 or k=1 and irem(n, 2)=0 then 0
else t:= 1-2*irem(n+k, 2);
T(n-t, k+t) + T(n, k-1)+T(n-1, k)
fi
end:
seq (`if` (irem(d, 2)=1,
seq (T(d-k, k), k=1..d-1),
seq (T(n, d-n), n=1..d-1)), d=2..11); # Alois P. Heinz, Feb 08 2011
MATHEMATICA
T[n_, k_] := T[n, k] = Module[{t}, Which[n<1 || k<1, 0, n == 1 && k == 1, 1, n == 1 && Mod[k, 2] == 1 || k == 1 && Mod[n, 2] == 0, 0, True, t = 1 - 2*Mod[n+k, 2]; T[n-t, k+t] + T[n, k-1] + T[n-1, k]]]; Table[If[Mod[d, 2] == 1, Table[T[d-k, k], {k, 1, d-1}], Table[T[n, d-n], {n, 1, d-1}]], {d, 2, 11}] // Flatten (* Jean-François Alcover, Jan 14 2014, translated from Alois P. Heinz's Maple code *)
CROSSREFS
Right-hand diagonal is A059294. Cf. A106243. Row sums give A106327.
Sequence in context: A104172 A091408 A193382 * A121474 A138003 A329232
KEYWORD
nonn,tabl,easy
AUTHOR
N. J. A. Sloane, May 29 2005
EXTENSIONS
More terms from Alois P. Heinz, Feb 08 2011
STATUS
approved