A106242 Same triangle as A106243, but with rows read in boustrophedon manner, i.e., in the order in which they were created.

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

Alois P. Heinz, Table of n, a(n) for n = 0..10010

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

Adjacent sequences: A106239 A106240 A106241 * A106243 A106244 A106245

Keyword

nonn,tabl,easy

Author

N. J. A. Sloane, May 29 2005

Extensions

More terms from Alois P. Heinz, Feb 08 2011

Status

approved