A274199 Limiting reverse row of the array A274190.

1, 1, 2, 3, 5, 8, 12, 19, 29, 44, 67, 101, 152, 228, 342, 511, 763, 1138, 1695, 2523, 3752, 5578, 8287, 12307, 18272, 27119, 40241, 59700, 88556, 131340, 194772, 288815, 428229, 634900, 941263, 1395397, 2068560, 3066372, 4545387, 6737633, 9987026, 14803303

Offset: 0

Author

Clark Kimberling, Jun 13 2016

Keywords

• nonn
• easy

Comments

The triangular array (g(n,k)) at A274190 is defined as follows: g(n,k) = 1 for n >= 0; g(n,k) = 0 if k > n; g(n,k) = g(n-1,k-1) + g(n-1,2k) for n > 0, k > 1.

From Gus Wiseman, Mar 12 2021: (Start)

Also (apparently) the number of compositions of n where all adjacent parts (x, y), satisfy x < 2y. For example, the a(1) = 1 through a(6) = 12 compositions are:

(1) (2) (3) (4) (5) (6)

(11) (12) (13) (14) (15)

(111) (22) (23) (24)

(112) (32) (33)

(1111) (113) (114)

(122) (123)

(1112) (132)

(11111) (222)

(1113)

(1122)

(11112)

(111111)

(End)

Examples

			Row (g(14,k)):  1, 51, 73, 69, 55, 40, 28, 19, 12, 8, 5, 3, 2, 1, 1; the reversal is 1 1 2 3 5 8 12 19 28 ..., which agrees with A274199 up to 19.
		

Links

• Daniel Gabric and Jeffrey Shallit, Smallest and Largest Block Palindrome Factorizations, arXiv:2302.13147 [math.CO], 2023.

Crossrefs

Cf. A274190, A274200, A274201.

Cf. A000929, A003242, A154402, A224957, A342094, A342095, A342096, A342097, A342098, A342191, A342330-A342342.

Programs

Mathematica

g[n_, 0] = g[n, 0] = 1;
g[n_, k_] := g[n, k] = If[k > n, 0, g[n - 1, k - 1] + g[n - 1, 2 k]];
z = 300; u = Reverse[Table[g[z, k], {k, 0, z}]];
z = 301; v = Reverse[Table[g[z, k], {k, 0, z}]];
w = Join[{1}, Intersection[u, v]] (* A274199 *)
Table[Length[Select[Join@@Permutations/@IntegerPartitions[n],And@@Table[#[[i]]<2*#[[i-1]],{i,2,Length[#]}]&]],{n,15}] (* Gus Wiseman, Mar 12 2021 *)