A130628 Related to the minimal number of periodic orbits of periods guaranteed by Sharkovskii's theorem.

1, 1, 0, 1, 0, 2, 0, 3, 0, 6, 1, 9, 2, 18, 4, 30, 8, 56, 16, 99, 32, 186, 64, 337, 128, 635, 256, 1177, 512, 2220, 1024, 4176, 2048, 7930, 4098, 15044, 8200, 28738, 16410, 54937, 32848, 105474, 65760, 202845, 131668, 391316, 263680, 756223, 528128

Offset

1,6

Comments

Bau-Sen Du's [1985/2007] Table 1, p. 6, has this sequence as the 6th column, denoted A_{n,5}.

Links

Table of n, a(n) for n=1..49.

Bau-Sen Du, The Minimal Number of Periodic Orbits of Periods Guaranteed in Sharkovskii's Theorem, arXiv:0706.2297 [math.DS], 2007; Bull. Austral. Math. Soc. 31(1985), 89-103. Corrigendum: 32 (1985), 159.

Mathematica

max = 50; Clear[b1, b2];
For[n = 1, n <= max, n++,
For[j = 1, j <= n, j++, b1[1][j, n] = 0; b1[2][j, n] = 1; b2[1][j, n] = b2[2][j, n] = 0]; b2[1][n, n] = b2[2][n, n] = 1];
For[k = 3, k <= max, k++,
For[n = 1, n <= max, n++,
For[j = 1, j <= n-1, j++, b1[k][j, n] = b1[k-2][1, n] + b1[k-2][j+1, n]; b2[k][j, n] = b2[k-2][1, n] + b2[k-2][j+1, n]]; b1[k][n, n] = b1[k-2][1, n] + b1[k-1][n, n]; b2[k][n, n] = b2[k-2][1, n] + b2[k-1][n, n]]];
phin[n_] := Table[b2[m][n, n] + 2 Sum[If[m + 2 - 2j > 0, b1[m + 2 - 2j][j, n], 0], {j, 1, n}], {m, 1, max}];
MT[s_List] := Table[DivisorSum[n, MoebiusMu[#] s[[n/#]] &]/n, {n, 1, Length[s]}];
MT[phin[5]] (* Jean-François Alcover, Nov 06 2018, adapted from Max Alekseyev's PARI script *)

Prog

(PARI) \\ implementation of MT() and phin() is given in A006207
MT(phin(5)) \\ sequence A_{n, 5} \\ Max Alekseyev

Crossrefs

Cf. A006206 (A_{n,1}), A006207 (A_{n,2}), A006208 (A_{n,3}), A006209 (A_{n,4}), A208092 (A_{n,6}), A006210 (D_{n,2}), A006211 (D_{n,3}), A094392.

Sequence in context: A208092 A081155 A348075 * A249431 A331176 A076563

Adjacent sequences: A130625 A130626 A130627 * A130629 A130630 A130631

Keyword

nonn

Author

Jonathan Vos Post, Jun 18 2007

Extensions

Terms a(32) onward from Max Alekseyev, Feb 23 2012

Status

approved