cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A060167 Number of orbits of length n under the map whose periodic points are counted by A001642.

Original entry on oeis.org

1, 1, 1, 2, 4, 5, 9, 13, 23, 36, 63, 101, 175, 290, 497, 840, 1445, 2460, 4247, 7293, 12619, 21805, 37856, 65695, 114401, 199280, 347944, 607959, 1064130, 1864083, 3269948, 5740840, 10090148, 17748870, 31250297, 55063603, 97102485, 171355485, 302605780, 534729160, 945513850
Offset: 1

Views

Author

Thomas Ward, Mar 13 2001

Keywords

Comments

The sequence A001642 seems to record the number of points of period n under a map. The number of orbits of length n for this map gives the sequence above.

Examples

			u(7) = 9 since a map whose periodic points are counted by A001642 would have 1 fixed point and 64 points of period 7, hence 9 orbits of length 7.
		

Crossrefs

Programs

  • PARI
    a001642(n) = if(n<0, 0, polcoeff(x*(1+2*x+4*x^3+5*x^4)/(1-x-x^2-x^4-x^5)+x*O(x^n), n));
    a(n) = (1/n)*sumdiv(n, d, moebius(d)*a001642(n/d)); \\ Michel Marcus, Sep 11 2017

Formula

a(n) = (1/n)* Sum_{ d divides n } mu(d)*A001642(n/d).

Extensions

More terms from Michel Marcus, Sep 11 2017

A113676 Number of elements of rows of Golomb's sequence A001462, with one less 2, interpreted as triangle: Start with first row 1. The row sum of row n-1 gives the number of elements taken from A001642 (one less 2) of row n.

Original entry on oeis.org

1, 1, 2, 6, 27, 234, 6202, 1084009, 4362192095
Offset: 1

Views

Author

Floor van Lamoen and Paul D. Hanna, Nov 06 2005

Keywords

Comments

a(n+1) gives row sum of row n of this triangle.
Conjecture: a(n) for n>1 gives first differences of Lionel Levine's sequence A014644(n) for n>=3.
Conjecture: Final elements of the rows form A014644 except for duplicate 2.

Examples

			The triangle begins
  1;
  2;
  3,3;
  4,4,4,5,5,5;
  ...
Row 4: [4,4,4,5,5,5] is generated from row 3: [3,3] because there are (3) 4's and (3) 5's in row 4.
		

A060168 Number of orbits of length n under the map whose periodic points are counted by A001643.

Original entry on oeis.org

1, 1, 1, 2, 4, 6, 10, 15, 26, 42, 74, 121, 212, 357, 620, 1064, 1856, 3209, 5618, 9794, 17192, 30153, 53114, 93554, 165308, 292250, 517802, 918207, 1630932, 2899434, 5161442, 9196168, 16402764, 29281168, 52319364, 93555601, 167427844, 299841117, 537357892, 963641588, 1729192432
Offset: 1

Views

Author

Thomas Ward, Mar 13 2001

Keywords

Comments

The sequence A001643 seems to record the number of points of period n under a map. The number of orbits of length n for this map gives the sequence above.

Examples

			u(7) = 10 since a map whose periodic points are counted by A001643 would have 1 fixed point and 71 points of period 7, hence 10 orbits of length 7.
		

Crossrefs

Programs

  • PARI
    a001643(n) = if(n<0, 0, polcoeff(x*(1+2*x+4*x^3+5*x^4+6*x^5)/(1-x-x^2-x^4-x^5-x^6)+x*O(x^n), n))
    a(n) = (1/n)*sumdiv(n, d, moebius(d)*a001643(n/d)); \\ Michel Marcus, Sep 11 2017

Formula

a(n) = (1/n)* Sum_{ d divides n } mu(d)*A001643(n/d).

Extensions

More terms from Michel Marcus, Sep 11 2017

A060169 Number of orbits of length n under the automorphism of the 3-torus whose periodic points are counted by A001945.

Original entry on oeis.org

1, 0, 0, 1, 0, 1, 1, 0, 2, 1, 2, 2, 2, 4, 4, 5, 8, 6, 12, 13, 16, 23, 26, 35, 46, 54, 76, 89, 120, 154, 192, 255, 322, 411, 544, 679, 898, 1145, 1476, 1925, 2466, 3201, 4156, 5338, 6978, 8985
Offset: 1

Views

Author

Thomas Ward, Mar 13 2001

Keywords

Comments

The sequence A001945 records the number of points of period n under a map. The number of orbits of length n for this map gives the sequence above.

Examples

			u(17) = 8 since the map whose periodic points are counted by A001945 has 1 fixed point and 137 points of period 17, hence 8 orbits of length 7.
		

Crossrefs

Formula

a(n) = (1/n)* Sum_{ d divides n } mu(d)*A001945(n/d).
Showing 1-4 of 4 results.