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 1-8 of 8 results.

A129766 Triangular array read by rows, made up of traditional exceptional groups plus A1: as A1,G2,F4,E6,E7,E8 as m(i) exponents as in A005556, A005763, A005776.

Original entry on oeis.org

1, 1, 5, 1, 5, 7, 11, 1, 4, 5, 7, 8, 11, 1, 5, 7, 9, 11, 13, 17, 1, 7, 11, 13, 17, 19, 23, 29
Offset: 1

Views

Author

Roger L. Bagula, May 16 2007

Keywords

Comments

Extra condition of group dimension: b[n] = a[n] + 1 ; DimGroup = Apply[Plus, b[n]]; Table[Apply[Plus, b[n]], {n, 0, 5}] {3, 14, 52, 78, 133, 248} Extra condition of Betti sum: Table[Apply[Plus, CoefficientList[Expand[Product[(1 + t^(2*a[i][[n]] + 1)), {n, 1,Length[a[i]]}]], t]], {i, 0, 5}] {2, 4, 16, 64, 128, 256} These exponents are necessary to the Poincaré polynomials for these exceptional groups.

Examples

			1;
1,5;
1,5,7,11;
1,4,5,7,8,11;
1,5,7,9,11,13,17;
1,7,11,13,17,19,23,29;
		

Crossrefs

Programs

  • Mathematica
    a[0] = {1}; a[1] = {1, 5}; a[2] = {1, 5, 7, 11}; a[3] = {1, 4, 5, 7, 8, 11}; a[4] = {1, 5, 7, 9, 11, 13, 17}; a[5] = {1, 7, 11, 13, 17, 19, 23, 29}; Flatten[Table[a[n], {n, 0, 5}]]

A005776 Exponents m_i associated with Weyl group W(E_8).

Original entry on oeis.org

1, 7, 11, 13, 17, 19, 23, 29
Offset: 1

Views

Author

Keywords

Comments

Numbers coprime to 30 in that number's reduced residue system. - Alonso del Arte, Oct 03 2017

References

  • H. S. M. Coxeter and W. O. J. Moser, Generators and Relations for Discrete Groups, 4th ed., Springer-Verlag, NY, reprinted 1984, p. 141.

Crossrefs

Programs

  • Magma
    Exponents(RootDatum("E8")); // Sergei Haller (sergei(AT)sergei-haller.de), Dec 21 2006
    
  • Mathematica
    Select[Range[30], GCD[30, #] == 1 &] (* Alonso del Arte, Oct 03 2017 *)
  • PARI
    select(n->gcd(n,30)==1, [1..29]) \\ Charles R Greathouse IV, Oct 17 2017

A106403 Primitive exponents of the Weyl group W(E_8).

Original entry on oeis.org

3, 15, 23, 27, 35, 39, 47, 59
Offset: 1

Views

Author

N. J. A. Sloane, May 30 2005

Keywords

References

  • C. Chevalley, The Betti numbers of the exceptional Lie groups, pp. 21-24 of Proc. Internat Congress Math., Cambridge 1950, Amer. Math. Soc., 1952.

Crossrefs

Formula

Equals 2*A005776(n) + 1.

A089011 a(n) = 1 if n is an exponent of the Weyl group W(E_7), 0 otherwise.

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Paul Boddington, Nov 03 2003

Keywords

Comments

The exponents are 1, 5, 7, 9, 11, 13, 17. The point of this sequence is that a similar generating function gives the exponents for any finite Coxeter group.

Crossrefs

Programs

  • PARI
    {a(n)=if(n<1, 0, polcoeff( x^17+x^13+x^11+x^9+x^7+x^5+x, n))} /* Michael Somos, Mar 07 2007 */

Formula

Euler transform of length 14 sequence [ 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, -1, 0, -1]. - Michael Somos, Mar 07 2007
G.f.: x*(1-x^12)*(1-x^14)/((1-x^4)*(1-x^6)).

A106373 Primitive exponents of the Weyl group W(E_6).

Original entry on oeis.org

3, 9, 11, 15, 17, 23
Offset: 1

Views

Author

N. J. A. Sloane, May 30 2005

Keywords

References

  • C. Chevalley, The Betti numbers of the exceptional Lie groups, pp. 21-24 of Proc. Internat Congress Math., Cambridge 1950, Amer. Math. Soc., 1952.

Crossrefs

Formula

Equals 2*A005556(n) + 1.

A106374 Primitive exponents of the Weyl group W(E_7).

Original entry on oeis.org

3, 11, 15, 19, 23, 27, 35
Offset: 1

Views

Author

N. J. A. Sloane, May 30 2005

Keywords

References

  • C. Chevalley, The Betti numbers of the exceptional Lie groups, pp. 21-24 of Proc. Internat Congress Math., Cambridge 1950, Amer. Math. Soc., 1952.

Crossrefs

Formula

Equals 2*A005763(n) + 1.

A118889 Ratio of Dimensions of the traditional Cartan exceptional group sequence A1,G2,F4,E6,E7,E8 to the Cartan matrix Dimension: Dimc={1, 2, 4, 6, 7, 8} DimG={3, 14, 52, 78, 133, 248} DimG/DimC={3, 7, 13, 13, 19, 31}.

Original entry on oeis.org

3, 7, 13, 13, 19, 31
Offset: 1

Views

Author

Roger L. Bagula, May 17 2007

Keywords

Comments

The sequence is inherently unordered, because there is no standard ordering of these groups. - R. J. Mathar, Dec 04 2011

Crossrefs

Programs

  • Mathematica
    (* Cartan Matrices: *)
    e[3] = {{2}};
    e[4] = {{2, -3}, {-1, 2}};
    e[5] = {{2, -1, 0, 0}, {-1, 2, -2, 0}, {0, -1, 2, -1}, {0, 0, -1, 2}};
    e[6] = {{2, 0, -1, 0, 0, 0}, {0, 2, 0, -1, 0, 0}, {-1, 0, 2, -1, 0, 0}, { 0, -1, -1, 2, -1, 0}, { 0, 0, 0, -1, 2, -1}, { 0, 0, 0, 0, -1, 2}};
    e[7] = {{2, 0, -1, 0, 0, 0, 0}, {0, 2, 0, -1, 0, 0, 0}, {-1, 0, 2, -1, 0, 0, 0}, {0, -1, -1, 2, -1, 0, 0}, {0, 0, 0, -1, 2, -1, 0}, { 0, 0, 0, 0, -1, 2, -1 }, { 0, 0, 0, 0, 0, -1, 2 }};
    e[8] = { {2, 0, -1, 0, 0, 0, 0, 0}, { 0, 2, 0, -1, 0, 0, 0, 0}, {-1, 0, 2, -1, 0, 0, 0, 0}, {0, -1, -1, 2, -1, 0, 0, 0}, {0, 0, 0, -1, 2, -1, 0, 0}, { 0, 0, 0, 0, -1, 2, -1, 0}, { 0, 0, 0, 0, 0, -1, 2, -1}, {0, 0, 0, 0, 0, 0, -1, 2}} ;
    a0 = Table[Length[CoefficientList[CharacteristicPolynomial[e[n], x], x]] - 1, {n, 3, 8}]; (* Poincaré Polynomials*)
    (*Poincaré polynomial exponents for G2, E6, E7, E8 from A005556, A005763, A005776 and Armand Borel's Essays in History of Lie Groups and Algebraic Groups*) (* b[n] = a[n] + 1 : DimGroup = Apply[Plus, b[n]]*)
    a[0] = {1};
    a[1] = {1, 5};
    a[2] = {1, 5, 7, 11};
    a[3] = {1, 4, 5, 7, 8, 11};
    a[4] = {1, 5, 7, 9, 11, 13, 17};
    a[5] = {1, 7, 11, 13, 17, 19, 23, 29};
    b0 = Table[Length[CoefficientList[Expand[Product[(1 + t^(2*a[i][[n]] + 1)), {n, 1, Length[a[i]]}]], t]] - 1, {i, 0, 5}];
    Table[b0[[n]]/a0[[n]], {n, 1, Length[a0]}]

Formula

P[n]=Poincare-Polynomial[n]=Product[1+t^A129766[m],{m,1,n}]
DimG[n]=Length[CoefficientList[P[n],t]]-1
Pc[n]=CharacteristicPolynomial[M[n],x]
DimC[n]=Length[CoefficientList[Pc[n],x]]-1
a[n]=DimG[n]/DimC[n]

A129769 Exponents m(i) for exceptional groups with best guesses for E7 1/2 and E9 added (there is a problem with the dimension of E9 as no sum of odd numbers will equal the 484, I get 483): triangular sequence is: A1,G2,F4,E6,E7 E7 1/2,E8,E9.

Original entry on oeis.org

1, 1, 5, 1, 5, 7, 11, 1, 4, 5, 7, 8, 11, 1, 5, 7, 9, 11, 13, 17, 1, 6, 9, 11, 13, 15, 17, 19, 1, 7, 11, 13, 17, 19, 23, 29, 1, 11, 17, 19, 23, 29, 31, 51, 55
Offset: 1

Views

Author

Roger L. Bagula, May 16 2007

Keywords

Comments

Betti number row sums: Table[Apply[Plus, CoefficientList[Expand[Product[(1 + t^(2*a[i][[n]] + 1)), {n, 1, Length[a[i]]}]], t]], {i, 0, 7}] {2, 4, 16, 64, 128, 256, 256, 512} Group dimensions sums: b[n_] = 2*a[n] + 1 Table[Apply[Plus, b[n]], {n, 0, 7}] {3, 14, 52, 78, 133, 190, 248, 483}.
From these exponents it is possible to get Poincaré polynomial estimates for the new E7 1/2 and E8 that best fit the pattern of the known exponents.

References

  • J. M. Landsberg, The sextonions and E_{7 1/2} (with L.Manivel) (Advances in Math 201(2006) p143 - 179) page 22; J. M. Landsberg, http://www.math.tamu.edu/~jml/LMsexpub.pdf: The sextonions and E_{7 1/2}
  • Armand Borel's Essays in History of Lie Groups and Algebraic Groups: gives G2 Poincaré polynomial, History of Mathematics, V. 21; http://www.amazon.com/Essays-History-Groups-Algebraic-Mathematics/dp/0821802887/ref=pd_rhf_p_3/104-0029617-0633535

Crossrefs

Programs

  • Mathematica
    a[0] = {1}; a[1] = {1, 5}; a[2] = {1, 5, 7, 11}; a[3] = {1, 4, 5, 7, 8, 11}; a[4] = {1, 5, 7, 9, 11, 13, 17}; a[5] = {1, 6, 9, 11, 13, 15, 17, 19}; a[6] = {1, 7, 11, 13, 17, 19, 23, 29}; a[7] = {1, 11, 17, 19, 23, 29, 31, 51, 55};

Formula

a(0) = {1}; a(1) = {1, 5}; a(2) = {1, 5, 7, 11}; a(3) = {1, 4, 5, 7, 8, 11}; a(4) = {1, 5, 7, 9, 11, 13, 17}; a(5) = {1, 6, 9, 11, 13, 15, 17, 19}; a(6) = {1, 7, 11, 13, 17, 19, 23, 29}; a(7) = {1, 11, 17, 19, 23, 29, 31, 51, 55};
Showing 1-8 of 8 results.