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 1-7 of 7 results.

A285548 Array read by antidiagonals: T(m,n) = number of step cyclic shifted sequences of length n using a maximum of m different symbols.

Original entry on oeis.org

1, 1, 2, 1, 3, 3, 1, 4, 6, 4, 1, 6, 10, 10, 5, 1, 6, 21, 20, 15, 6, 1, 13, 24, 55, 35, 21, 7, 1, 10, 92, 76, 120, 56, 28, 8, 1, 24, 78, 430, 201, 231, 84, 36, 9, 1, 22, 327, 460, 1505, 462, 406, 120, 45, 10, 1, 45, 443, 2605, 2015, 4291, 952, 666, 165, 55, 11
Offset: 1

Views

Author

Andrew Howroyd, Apr 20 2017

Keywords

Comments

See A056371, A002729 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent.
Equivalently, the number of mappings with domain {0..n-1} and codomain {1..m} up to equivalence. Mappings A and B are equivalent if there is a d, prime to n, and a t such that A(i) = B((i*d + t) mod n) for i in {0..n-1}.
All column sequences are polynomials of order n.

Examples

			Table starts:
1  1  1   1   1     1     1      1      1       1 ...
2  3  4   6   6    13    10     24     22      45 ...
3  6 10  21  24    92    78    327    443    1632 ...
4 10 20  55  76   430   460   2605   5164   26962 ...
5 15 35 120 201  1505  2015  14070  37085  246753 ...
6 21 56 231 462  4291  6966  57561 188866 1519035 ...
7 28 84 406 952 10528 20140 192094 752087 7079800 ...
...
		

References

  • M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Crossrefs

Programs

  • Mathematica
    IsLeastPoint[s_, f_] := Module[{t=f[s]}, While[t>s, t=f[t]]; Boole[s==t]];
    c[n_, k_, t_] := Sum[IsLeastPoint[u, Mod[#*k+t, n]&], {u, 0, n-1}];
    a[n_, x_] := Sum[If[GCD[k, n] == 1, x^c[n, k, t], 0], {t, 0, n-1}, {k, 1,
    n}] / (n*EulerPhi[n]);
    Table[a[n-m+1, m], {n, 1, 11}, {m, 1, n}] // Flatten (* Jean-François Alcover, Jun 05 2017, translated from PARI *)
  • PARI
    IsLeastPoint(s,f)={my(t=f(s)); while(t>s,t=f(t));s==t}
    C(n,k,t)=sum(u=0,n-1,IsLeastPoint(u,v->(v*k+t)%n));
    a(n,x)=sum(t=0, n-1, sum(k=1, n, if (gcd(k, n)==1, x^C(n,k,t),0)))/(n * eulerphi(n));
    for(m=1, 7, for(n=1, 10, print1( a(n,m), ", ") ); print(); );

A056411 Number of step cyclic shifted sequences using a maximum of three different symbols.

Original entry on oeis.org

3, 6, 10, 21, 24, 92, 78, 327, 443, 1632, 1698, 12769, 10464, 57840, 122822, 348222, 476052, 3597442, 3401970, 22006959, 41597374, 142677588, 186077886, 1476697627, 1694658003, 8147282460, 15690973754, 68149816689, 84520682160, 857935531804, 664166389302, 3620293575942, 8422974597554, 30656600391720, 59561470990362
Offset: 1

Views

Author

Keywords

Comments

See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent.

References

  • M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Crossrefs

Row 3 of A285548.
Cf. A002729.

Programs

  • Mathematica
    M[j_, L_] := Module[{m=1}, While[Sum[j^i, {i, 0, m-1}] ~Mod~ L != 0, m++]; m]; c[j_, t_, n_] := Sum[1/M[j, n/GCD[n, u*(j-1)+t]], {u, 0, n-1}]; CB[n_, k_] = If [n==1, k, 1/(n*EulerPhi[n])*Sum[If[1==GCD[n, j], k^c[j, t, n], 0], {t, 0, n-1}, {j, 1, n-1}]]; Table[Print[cb = CB[n, 3]]; cb, {n, 1, 35}] (* Jean-François Alcover, Dec 04 2015, after Joerg Arndt *)
  • PARI
    \\ see p.3 of the Dokovic et al. reference
    M(j,  L)={my(m=1); while ( sum(i=0, m-1, j^i) % L != 0, m+=1 ); m; }
    c(j, t, n)=sum(u=0,n-1, 1/M(j, n / gcd(n, u*(j-1)+t) ) );
    CB(n, k)=if (n==1,k, 1/(n*eulerphi(n)) * sum(t=0,n-1, sum(j=1,n-1, if(1==gcd(n,j), k^c(j,t,n), 0) ) ) );
    for(n=1, 66, print1(CB(n,3),", "));
    \\ second argument k=3, 4, 5, 6 respectively gives A056411, A056412, A056413, A056414.
    \\ Joerg Arndt, Aug 27 2014

Formula

Refer to Titsworth or slight "simplification" in Nester.

Extensions

Added more terms, Joerg Arndt, Aug 27 2014

A056374 Number of step shifted (decimated) sequences using a maximum of five different symbols.

Original entry on oeis.org

5, 25, 75, 375, 825, 8125, 13175, 103125, 327125, 2445625, 4884435, 61640625, 101732425, 1017323125, 3816215625, 19104609375, 47683838325, 635787765625, 1059638680675, 11924780390625, 39736963221875, 238418603522125, 541860418146375
Offset: 1

Views

Author

Keywords

Comments

See A056371 for an explanation of step shifts.

References

  • M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Crossrefs

Cf. A056413.
A row or column of A132191.

Programs

  • Mathematica
    a[m_, n_] := (1/EulerPhi[n])*Sum[If[GCD[k, n] == 1, m^DivisorSum[n, EulerPhi[#]/MultiplicativeOrder[k, #] &], 0], {k, 1, n}]; Table[a[5, n], {n, 1, 23}] (* Jean-François Alcover, Dec 04 2015 *)

Formula

The cycle index is implicit in Titsworth.
Sequences A056372-A056375 fit a general formula, implemented in PARI/GP as follows: { a(m,n) = sum(k=1, n, if(gcd(k, n)==1, m^sumdiv(n, d, eulerphi(d)/znorder(Mod(k, d))), 0); ) / eulerphi(n) }. - Max Alekseyev, Nov 08 2007

Extensions

More terms from Max Alekseyev, Nov 08 2007

A056432 Step cyclic shifted sequence structures using a maximum of five different symbols.

Original entry on oeis.org

1, 2, 3, 7, 8, 36, 35, 201, 393, 2370, 3971, 46094, 66675, 613439, 2139350, 10016839, 23424253, 294723254, 465082931, 4972761822, 15773188813, 90323063945, 196342666487, 2587522663248, 4967200045397, 39800811900389
Offset: 1

Views

Author

Keywords

Comments

See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent. Permuting the symbols will not change the structure.

References

  • M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Crossrefs

Cf. A056413.

Formula

Use de Bruijn's generalization of Polya's enumeration theorem as discussed in reference.

A056418 Number of step cyclic shifted sequences using exactly five different symbols.

Original entry on oeis.org

0, 0, 0, 0, 6, 150, 400, 4080, 15480, 127818, 269340, 3493680, 5777190, 57262450, 210945182, 1030388115, 2493913170, 32176448060, 51785999300, 562228325904, 1805427491920, 10438821843750, 22865672706000
Offset: 1

Views

Author

Keywords

Comments

See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent.

References

  • M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Crossrefs

Cf. A056413.

Formula

A056413(n)-5*A056412(n)+10*A056411(n)-10*A002729(n)+5.

A056419 Number of step cyclic shifted sequences using exactly six different symbols.

Original entry on oeis.org

0, 0, 0, 0, 0, 60, 360, 6030, 35280, 410976, 1174896, 19948200, 43022700, 543757860, 2524673904, 15399118440, 46338868800, 737917466160, 1459120076400, 19381180990752, 75959665269840, 534453892557660
Offset: 1

Views

Author

Keywords

Comments

See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent.

References

  • M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Crossrefs

Cf. A056414.

Formula

A056414(n)-6*A056413(n)+15*A056412(n)-20*A056411(n)+15*A002729(n)-6.

A056422 Number of primitive (period n) step cyclic shifted sequences using a maximum of five different symbols.

Original entry on oeis.org

5, 10, 30, 105, 196, 1460, 2010, 13950, 37050, 246542, 445510, 5204180, 7832180, 72701620, 254689426, 1196199375, 2805046960, 35322773200, 55770979190, 596439488166, 1892294576710, 10837222569140
Offset: 1

Views

Author

Keywords

Comments

See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent.

References

  • M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Formula

Sum mu(d)*A056413(n/d) where d|n.
Showing 1-7 of 7 results.