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 1-10 of 17 results. Next

A173407 Partial sums of A002106.

Original entry on oeis.org

1, 2, 4, 9, 14, 30, 37, 87, 121, 166, 174, 475, 484, 547, 651, 2605, 2615, 3598, 3606, 4723, 4887, 4946, 4953, 29953, 30164, 30260, 32652, 34506, 34514, 40226, 40238, 2841562, 2841724, 2841839, 2842246, 2963525, 2963536, 2963612, 2963918, 3279760, 3279770, 3289261, 3289271, 3291384, 3302307, 3302363, 3302369
Offset: 1

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Author

Jonathan Vos Post, Feb 17 2010

Keywords

Comments

Partial sums of number of transitive permutation groups of degree n. The subsequence of primes in this partial sum begins: 2, 37, 547, 4723. The subsequence of squares in this partial sum begins: 1, 4, 9, 121, 484.

Crossrefs

Programs

Formula

a(n) = Sum_{i=1..n} A002106(i).

Extensions

More terms from Jinyuan Wang, Feb 23 2020
More terms from Vaclav Kotesovec, Jul 18 2022

A000001 Number of groups of order n.

Original entry on oeis.org

0, 1, 1, 1, 2, 1, 2, 1, 5, 2, 2, 1, 5, 1, 2, 1, 14, 1, 5, 1, 5, 2, 2, 1, 15, 2, 2, 5, 4, 1, 4, 1, 51, 1, 2, 1, 14, 1, 2, 2, 14, 1, 6, 1, 4, 2, 2, 1, 52, 2, 5, 1, 5, 1, 15, 2, 13, 2, 2, 1, 13, 1, 2, 4, 267, 1, 4, 1, 5, 1, 4, 1, 50, 1, 2, 3, 4, 1, 6, 1, 52, 15, 2, 1, 15, 1, 2, 1, 12, 1, 10, 1, 4, 2
Offset: 0

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Author

Keywords

Comments

Also, number of nonisomorphic subgroups of order n in symmetric group S_n. - Lekraj Beedassy, Dec 16 2004
Also, number of nonisomorphic primitives (antiderivatives) of the combinatorial species Lin[n-1], or X^{n-1}; see Rajan, Summary item (i). - Nicolae Boicu, Apr 29 2011
In (J. H. Conway, Heiko Dietrich and E. A. O'Brien, 2008), a(n) is called the "group number of n", denoted by gnu(n), and the first occurrence of k is called the "minimal order attaining k", denoted by moa(k) (see A046057). - Daniel Forgues, Feb 15 2017
It is conjectured in (J. H. Conway, Heiko Dietrich and E. A. O'Brien, 2008) that the sequence n -> a(n) -> a(a(n)) = a^2(n) -> a(a(a(n))) = a^3(n) -> ... -> consists ultimately of 1s, where a(n), denoted by gnu(n), is called the "group number of n". - Muniru A Asiru, Nov 19 2017
MacHale (2020) shows that there are infinitely many values of n for which there are more groups than rings of that order (cf. A027623). He gives n = 36355 as an example. It would be nice to have enough values of n to create an OEIS entry for them. - N. J. A. Sloane, Jan 02 2021
I conjecture that a(i) * a(j) <= a(i*j) for all nonnegative integers i and j. - Jorge R. F. F. Lopes, Apr 21 2024

Examples

			Groups of orders 1 through 10 (C_n = cyclic, D_n = dihedral of order n, Q_8 = quaternion, S_n = symmetric):
1: C_1
2: C_2
3: C_3
4: C_4, C_2 X C_2
5: C_5
6: C_6, S_3=D_6
7: C_7
8: C_8, C_4 X C_2, C_2 X C_2 X C_2, D_8, Q_8
9: C_9, C_3 X C_3
10: C_10, D_10
		

References

  • S. R. Blackburn, P. M. Neumann, and G. Venkataraman, Enumeration of Finite Groups, Cambridge, 2007.
  • L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 302, #35.
  • J. H. Conway et al., The Symmetries of Things, Peters, 2008, p. 209.
  • H. S. M. Coxeter and W. O. J. Moser, Generators and Relations for Discrete Groups, 4th ed., Springer-Verlag, NY, reprinted 1984, p. 134.
  • CRC Standard Mathematical Tables and Formulae, 30th ed. 1996, p. 150.
  • R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics, A Foundation for Computer Science, Addison-Wesley Publ. Co., Reading, MA, 1989, Section 6.6 'Fibonacci Numbers' pp. 281-283.
  • M. Hall, Jr. and J. K. Senior, The Groups of Order 2^n (n <= 6). Macmillan, NY, 1964.
  • D. Joyner, 'Adventures in Group Theory', Johns Hopkins Press. Pp. 169-172 has table of groups of orders < 26.
  • D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, Section XIII.24, p. 481.
  • M. F. Newman and E. A. O'Brien, A CAYLEY library for the groups of order dividing 128. Group theory (Singapore, 1987), 437-442, de Gruyter, Berlin-New York, 1989.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

The main sequences concerned with group theory are A000001 (this one), A000679, A001034, A001228, A005180, A000019, A000637, A000638, A002106, A005432, A000688, A060689, A051532.
A003277 gives n for which A000001(n) = 1, A063756 (partial sums).
A046057 gives first occurrence of each k.
A027623 gives the number of rings of order n.

Programs

  • GAP
    A000001 := Concatenation([0], List([1..500], n -> NumberSmallGroups(n))); # Muniru A Asiru, Oct 15 2017
  • Magma
    D:=SmallGroupDatabase(); [ NumberOfSmallGroups(D, n) : n in [1..1000] ]; // John Cannon, Dec 23 2006
    
  • Maple
    GroupTheory:-NumGroups(n); # with(GroupTheory); loads this command - N. J. A. Sloane, Dec 28 2017
  • Mathematica
    FiniteGroupCount[Range[100]] (* Harvey P. Dale, Jan 29 2013 *)
    a[ n_] := If[ n < 1, 0, FiniteGroupCount @ n]; (* Michael Somos, May 28 2014 *)

Formula

From Mitch Harris, Oct 25 2006: (Start)
For p, q, r primes:
a(p) = 1, a(p^2) = 2, a(p^3) = 5, a(p^4) = 14, if p = 2, otherwise 15.
a(p^5) = 61 + 2*p + 2*gcd(p-1,3) + gcd(p-1,4), p >= 5, a(2^5)=51, a(3^5)=67.
a(p^e) ~ p^((2/27)e^3 + O(e^(8/3))).
a(p*q) = 1 if gcd(p,q-1) = 1, 2 if gcd(p,q-1) = p. (p < q)
a(p*q^2) is one of the following:
---------------------------------------------------------------------------
| a(p*q^2) | p*q^2 of the form | Sequences (p*q^2) |
---------- ------------------------------------------ ---------------------
| (p+9)/2 | q == 1 (mod p), p odd | A350638 |
| 5 | p=3, q=2 => p*q^2 = 12 |Special case with A_4|
| 5 | p=2, q odd | A143928 |
| 5 | p == 1 (mod q^2) | A350115 |
| 4 | p == 1 (mod q), p > 3, p !== 1 (mod q^2) | A349495 |
| 3 | q == -1 (mod p), p and q odd | A350245 |
| 2 | q !== +-1 (mod p) and p !== 1 (mod q) | A350422 |
---------------------------------------------------------------------------
[Table from Bernard Schott, Jan 18 2022]
a(p*q*r) (p < q < r) is one of the following:
q == 1 (mod p) r == 1 (mod p) r == 1 (mod q) a(p*q*r)
-------------- -------------- -------------- --------
No No No 1
No No Yes 2
No Yes No 2
No Yes Yes 4
Yes No No 2
Yes No Yes 3
Yes Yes No p+2
Yes Yes Yes p+4
[table from Derek Holt].
(End)
a(n) = A000688(n) + A060689(n). - R. J. Mathar, Mar 14 2015

Extensions

More terms from Michael Somos
Typo in b-file description fixed by David Applegate, Sep 05 2009

A000019 Number of primitive permutation groups of degree n.

Original entry on oeis.org

1, 1, 2, 2, 5, 4, 7, 7, 11, 9, 8, 6, 9, 4, 6, 22, 10, 4, 8, 4, 9, 4, 7, 5, 28, 7, 15, 14, 8, 4, 12, 7, 4, 2, 6, 22, 11, 4, 2, 8, 10, 4, 10, 4, 9, 2, 6, 4, 40, 9, 2, 3, 8, 4, 8, 9, 5, 2, 6, 9, 14, 4, 8, 74, 13, 7, 10, 7, 2, 2, 10, 4, 16, 4, 2, 2, 4, 6, 10, 4, 155, 10, 6, 6, 6, 2, 2, 2, 10, 4, 10, 2
Offset: 1

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Author

Keywords

Comments

A check found errors in Theißen's data (degree 121 and 125) as well as in Short's work (degree 169). - Alexander Hulpke, Feb 19 2002
There is an error at n=574 in the Dixon-Mortimer paper. - Colva M. Roney-Dougal.

References

  • CRC Handbook of Combinatorial Designs, 1996, pp. 595ff.
  • K. Harada and H. Yamaki, The irreducible subgroups of GL_n(2) with n <= 6, C. R. Math. Rep. Acad. Sci. Canada 1, 1979, 75-78.
  • A. Hulpke, Konstruktion transitiver Permutationsgruppen, Dissertation, RWTH Aachen, 1996.
  • M. W. Short, The Primitive Soluble Permutation Groups of Degree less than 256, LNM 1519, 1992, Springer
  • C. C. Sims, Computational methods in the study of permutation groups, pp. 169-183 of J. Leech, editor, Computational Problems in Abstract Algebra. Pergamon, Oxford, 1970.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • H. Theißen, Eine Methode zur Normalisatorberechnung in Permutationsgruppen mit Anwendungen in der Konstruktion primitiver Gruppen, Dissertation, RWTH, RWTH-A, 1997 [But see comment above about errors! ]

Crossrefs

Programs

  • GAP
    List([2..2499],NrPrimitiveGroups);
    
  • Magma
    [NumberOfPrimitiveGroups(i) : i in [1..4095]];

Extensions

More terms and additional references from Alexander Hulpke

A000637 Number of fixed-point-free permutation groups of degree n.

Original entry on oeis.org

1, 0, 1, 2, 7, 8, 37, 40, 200, 258, 1039, 1501, 7629, 10109, 54322, 83975, 527036, 780193, 5808293
Offset: 0

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Author

Keywords

Comments

a(1) = 0 since the trivial group of degree 1 has a fixed point. One could also argue that one should set a(1) = 1 by convention.

References

  • G. Butler and J. McKay, The transitive groups of degree up to eleven, Comm. Algebra, 11 (1983), 863-911.
  • D. Holt, Enumerating subgroups of the symmetric group. Computational Group Theory and the Theory of Groups, II, edited by L.-C. Kappe, A. Magidin and R. Morse. AMS Contemporary Mathematics book series, vol. 511, pp. 33-37.
  • A. Hulpke, Konstruktion transitiver Permutationsgruppen, Dissertation, RWTH Aachen, 1996.
  • A. Hulpke, Constructing transitive permutation groups, J. Symbolic Comput. 39 (2005), 1-30.
  • A. Hulpke, Constructing Transitive Permutation Groups, in preparation
  • C. C. Sims, Computational methods in the study of permutation groups, pp. 169-183 of J. Leech, editor, Computational Problems in Abstract Algebra. Pergamon, Oxford, 1970.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A000019, A002106. Unlabeled version of A116693.

Formula

a(n) = A000638(n) - A000638(n-1). - Christian G. Bower, Feb 23 2006

Extensions

More terms from Alexander Hulpke
a(2) and a(10) corrected, a(11) and a(12) added by Christian G. Bower, Feb 23 2006
Terms a(13)-a(18) were computed by Derek Holt and contributed by Alexander Hulpke, Jul 30 2010, who comments that he has verified the terms up through a(16).
Edited by N. J. A. Sloane, Jul 30 2010, at the suggestion of Michael Somos

A186277 a(n) is the number of transitive Galois groups for polynomials of degree p = prime(n).

Original entry on oeis.org

1, 2, 5, 7, 8, 9, 10, 8, 7, 8, 12, 11, 10, 10, 6, 8, 6, 14, 10, 10, 16, 10, 6, 10, 14, 11, 10, 6, 14, 12, 15, 10, 10, 10, 8, 14, 14, 12, 6, 8, 6, 20, 10, 16, 11, 14, 18, 10, 6, 14, 10, 10, 22, 10, 15, 6, 8, 18, 14, 18, 10, 8, 15, 10, 18, 8, 18, 22, 6, 14, 14, 6, 10, 14, 18, 6, 8, 20, 17, 18, 10, 26, 10, 22, 10, 10, 16, 18, 14, 18, 6, 6, 14, 14, 10, 6, 8, 18, 14, 26, 18, 8, 6, 10, 18, 23, 6, 12, 10, 26, 10, 20, 18, 10
Offset: 1

Views

Author

Artur Jasinski, Feb 16 2011

Keywords

Crossrefs

Cf. A002106.

Programs

  • Magma
    [NumberOfPrimitiveGroups(NthPrime(i)) : i in [1..100]]; // Vincenzo Librandi, Dec 31 2019

Formula

a(n) = A002106(prime(n)).

A001051 Number of subgroups of order n in orthogonal group O(3).

Original entry on oeis.org

1, 3, 1, 5, 1, 5, 1, 7, 1, 5, 1, 8, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 10, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 8, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 8, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 7, 1, 5, 1, 8
Offset: 1

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Author

Keywords

Crossrefs

The main sequences concerned with group theory are A000001, A000679, A001034, A001051, A001228, A005180, A000019, A000637, A000638, A002106, A005432, A051881.

Programs

  • Mathematica
    a[2] = 3; a[4] = 5; a[12] = 8; a[24] = 10; a[48] = a[60] = a[120] = 8; a[n_] := Switch[Mod[n, 4], 0, 7, 1, 1, 2, 5, 3, 1]; Table[a[n], {n, 1, 96}] (* Jean-François Alcover, Oct 15 2013 *)
  • PARI
    A001051(n) = if((12==n)||(48==n)||(60==n)||(120==n),8,if(24==n,10,if((4==n)||(2==n),1+n,[1,5,1,7][1+((n-1)%4)]))); \\ Antti Karttunen, Jan 15 2019

Formula

Has period 1 5 1 7 except that a(2) = 3, a(4) = 5, a(12) = 8, a(24) = 10, a(48) = a(60) = a(120) = 8.

Extensions

Data section extended up to a(120) by Antti Karttunen, Jan 15 2019

A051881 Number of subgroups of order n in special orthogonal group SO(3).

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1
Offset: 1

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Author

Keywords

Examples

			The groups are "nn", of order n; "22n", of order 2n; "332", "432", "532" of orders 12,24,60.
		

Crossrefs

The main sequences concerned with group theory are A000001, A000679, A001034, A001051, A001228, A005180, A000019, A000637, A000638, A002106, A005432, A051881.

Programs

  • Mathematica
    a[2] = 1; a[12|24|60] = 3; a[n_] := 2-Mod[n, 2]; Array[a, 105] (* Jean-François Alcover, Nov 12 2015 *)
  • PARI
    a(n)=if(n==2||n==12||n==24||n==60, if(n>2,3,1), if(n%2,1,2)) \\ Charles R Greathouse IV, Nov 10 2015
    
  • Python
    def a(n):
        if n == 2:
            return 1
        elif n in {12, 24, 60}:
            return 3
        else:
            return 2 - n % 2 # Paul Muljadi, Oct 21 2024

Formula

Has period 1, 2 except for a(2) = 1, a(12) = a(24) = a(60) = 3.

Extensions

More terms from James Sellers and David W. Wilson, Dec 16 1999

A124938 Number of non-solvable transitive Galois groups for polynomials of degree n.

Original entry on oeis.org

0, 0, 0, 0, 2, 4, 3, 5, 4, 21, 4, 36, 3, 27, 40, 49, 5, 91, 2, 358, 56, 27, 3, 807, 79, 26, 64, 617, 2, 1896, 4
Offset: 1

Views

Author

Artur Jasinski, Nov 13 2006

Keywords

Comments

This sequence is A002106 (total number of transitive Galois groups) - A124937 (number of solvable transitive groups).

Examples

			a(5) = 2: for polynomials of degree 5 we have 2 non-solvable groups: A_5 (T5_4) and S_5 (T5_5)
		

Crossrefs

Programs

  • GAP
    "a(15)= "; l:=AllTransitiveGroups(NrMovedPoints,15,IsSolvable,false); # Artur Jasinski, Feb 04 2007
    
  • Magma
    for g in [1..45] do
    G:=TransitiveGroup(10,g);
    IsSolvable(G);
    end for; /* Artur Jasinski, Dec 03 2013 */

Formula

a(n) = A002106(n) - A124937(n). - Michel Marcus, Nov 06 2013

Extensions

More terms from Artur Jasinski, Feb 04 2007
a(10) and a(12) corrected by Artur Jasinski, Dec 03 2013
More terms from Alois P. Heinz, Feb 02 2014

A173397 Partial sums of A000019.

Original entry on oeis.org

1, 2, 4, 6, 11, 15, 22, 29, 40, 49, 57, 63, 72, 76, 82, 104, 114, 118, 126, 130, 139, 143, 150, 155, 183, 190, 205, 219, 227, 231, 243, 250, 254, 256, 262, 284, 295, 299, 301, 309, 319, 323, 333, 337, 346, 348, 354, 358, 398, 407, 409, 412, 420, 424, 432, 441
Offset: 1

Views

Author

Jonathan Vos Post, Feb 17 2010

Keywords

Comments

Partial sums of number of primitive permutation groups of degree n. The subsequence of primes in this partial sum begins: 2, 11, 29, 139, 227, 337, 409, 463, 563, 593, 821, 853, 881 (and other powers include 243). The subsequence of squares in this partial sum begins: 1, 4, 49, 256, 441, 576.

Crossrefs

Programs

Formula

a(n) = Sum_{i=1..n} A000019(i).

A177244 Number of different orders of transitive groups for polynomials of degree n.

Original entry on oeis.org

1, 1, 2, 4, 5, 11, 7, 19, 19, 26, 8, 62, 9, 39, 46, 90, 10, 127, 8, 144, 84, 40, 7, 366, 79, 47, 183, 251, 8, 466, 12, 487
Offset: 1

Views

Author

Artur Jasinski, May 06 2010

Keywords

Comments

Total number of transitive groups for polynomial of degree n is given by A002106.

Examples

			a(4) = 4 because we have 4 different orders of transitive groups for polynomial of degree 4.
These orders are 4, 8, 12, 24 (total number of groups is 5 but two have that same order 4).
		

Crossrefs

Cf. A002106.

Extensions

a(16)-a(32) from Artur Jasinski, Feb 19 2011
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