A378307 a(n) is the number of terms in row n of the array A378303.

1, 1, 2, 4, 6, 9, 14, 21, 31, 48, 71, 105, 159, 237, 358, 538, 808, 1212, 1821, 2731, 4098, 6148, 9221, 13829, 20742, 31107, 46672, 70004, 104968, 157463, 236181, 354207, 531340, 796994, 1195379, 1793124, 2689738, 4034554, 6051988, 9077930

Offset: 1

Author

Clark Kimberling, Dec 21 2024

Keywords

• nonn

Examples

			First eight rows of array A378303:
   1
   2
   2, 2
   1  1  2  2
   2  1  2  2  1  1
   2  2  1  2  2  1  1  2  1
   1  1  2  2  1  2  2  1  1  2  1  2  2  1
   2  1  2  2  1  1  2  1  1  2  2  1  2  1  1  2  1  1  2  2  1
   a(8) = 26 = number of terms in row 8.
		

Crossrefs

Cf. A378282, A378303.

Programs

Mathematica

z = 47;
invRE[seq_, k_] :=
  Flatten[Map[ConstantArray[#[[2]], #[[1]]] &,
    Partition[Riffle[seq, {k, 2 - Mod[k + 1, 2]}, {2, -1, 2}], 2]]];
row1 = {1}; rows = {row1};
col = PadRight[{}, z, {1, 2, 2}]
Do[AppendTo[rows, invRE[Last[rows], col[[n]]]], {n, 2, Length[col]}]
Map[Length, rows]