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 12 results. Next

A231867 Number of perfect groups of order A060793(n).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 7, 1, 1, 1, 1, 3, 1, 1, 1, 7, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 5, 1, 1, 3, 1, 1, 9, 4, 1, 1, 1, 1, 1, 1, 3, 1, 7, 1, 1, 1, 1, 5, 22, 1, 3, 1, 1, 1, 1, 1, 4, 1, 1, 37, 2, 1, 1, 4, 1, 1, 1, 4, 25, 3, 1, 1, 1, 3, 1
Offset: 1

Views

Author

Eric M. Schmidt, Nov 14 2013

Keywords

Crossrefs

Cf. A131932.

Programs

  • GAP
    A231867 := n -> NrPerfectGroups(SizesPerfectGroups()[n]); # works for most n <= 331.

A098136 Duplicate of A060793.

Original entry on oeis.org

1, 60, 120, 168, 336, 360, 504, 660, 720, 960, 1080, 1092, 1320, 1344, 1920, 2160, 2184
Offset: 1

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Author

Keywords

A121513 Partial sums of orders of finite perfect groups (A060793).

Original entry on oeis.org

1, 61, 181, 349, 685, 1045, 1549, 2209, 2929, 3889, 4969, 6061, 7381, 8725, 10645, 12805, 14989, 17437, 19957, 22645, 25645, 29065, 32665, 36505, 40585, 45445, 50341, 55381, 60757, 66373, 72133, 78181, 84253, 91093, 98293, 105793, 113353
Offset: 1

Views

Author

Jonathan Vos Post, Sep 07 2006

Keywords

Crossrefs

Cf. A060793.

Formula

a(n) = SUM[i=1..n]A060793(i).

A001034 Orders of noncyclic simple groups (without repetition).

Original entry on oeis.org

60, 168, 360, 504, 660, 1092, 2448, 2520, 3420, 4080, 5616, 6048, 6072, 7800, 7920, 9828, 12180, 14880, 20160, 25308, 25920, 29120, 32736, 34440, 39732, 51888, 58800, 62400, 74412, 95040, 102660, 113460, 126000, 150348, 175560, 178920
Offset: 1

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Author

Keywords

Comments

An alternative definition, to assist in searching: Orders of non-cyclic finite simple groups.
This comment is about the three sequences A001034, A060793, A056866: The Feit-Thompson theorem says that a finite group with odd order is solvable, hence all numbers in this sequence are even. - Ahmed Fares (ahmedfares(AT)my-deja.com), May 08 2001 [Corrected by Isaac Saffold, Aug 09 2021]
The primitive elements are A257146. These are also the primitive elements of A056866. - Charles R Greathouse IV, Jan 19 2017
Conjecture: This is a subsequence of A083207 (Zumkeller numbers). Verified for n <= 156. A fast provisional test was used, based on Proposition 17 from Rao/Peng JNT paper (see A083207). For those few cases where the fast test failed (such as 2588772 and 11332452) the comprehensive (but much slower) test by T. D. Noe at A083207 was used for result confirmation. - Ivan N. Ianakiev, Jan 11 2020
From M. Farrokhi D. G., Aug 11 2020: (Start)
The conjecture is not true. The smallest and the only counterexample among the first 457 terms of the sequence is a(175) = 138297600.
On the other hand, the orders of sporadic simple groups are Zumkeller. And with the exception of the smallest two orders 7920 and 95040, the odd part of the other orders are also Zumkeller. (End)
Every term in this sequence is divisible by 4*p*q, where p and q are distinct odd primes. - Isaac Saffold, Oct 24 2021

References

  • J. H. Conway, R. T. Curtis, S. P. Norton, R. A. Parker and R. A. Wilson, ATLAS of Finite Groups. Oxford Univ. Press, 1985 [for best online version see https://oeis.org/wiki/Welcome#Links_to_Other_Sites].
  • Dickson L.E. Linear groups, with an exposition of the Galois field theory (Teubner, 1901), p. 309.
  • M. Hall, Jr., A search for simple groups of order less than one million, pp. 137-168 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. A109379 (orders with repetition), A119648 (orders that are repeated).

A056866 Orders of non-solvable groups, i.e., numbers that are not solvable numbers.

Original entry on oeis.org

60, 120, 168, 180, 240, 300, 336, 360, 420, 480, 504, 540, 600, 660, 672, 720, 780, 840, 900, 960, 1008, 1020, 1080, 1092, 1140, 1176, 1200, 1260, 1320, 1344, 1380, 1440, 1500, 1512, 1560, 1620, 1680, 1740, 1800, 1848, 1860, 1920, 1980, 2016, 2040
Offset: 1

Views

Author

N. J. A. Sloane, Sep 02 2000

Keywords

Comments

A number is solvable if every group of that order is solvable.
This comment is about the three sequences A001034, A060793, A056866: The Feit-Thompson theorem says that a finite group with odd order is solvable, hence all numbers in this sequence are even. - Ahmed Fares (ahmedfares(AT)my-deja.com), May 08 2001 [Corrected by Isaac Saffold, Aug 09 2021]
Insoluble group orders can be derived from A001034 (simple non-cyclic orders): k is an insoluble order iff k is a multiple of a simple non-cyclic order. - Des MacHale
All terms are divisible by 4 and either 3 or 5. - Charles R Greathouse IV, Sep 11 2012
Subsequence of A056868 and hence of A060652. - Charles R Greathouse IV, Apr 16 2015, updated Sep 11 2015
The primitive elements are A257146. Since the sum of the reciprocals of the terms of that sequence converges, this sequence has a natural density and so a(n) ~ k*n for some k (see, e.g., Erdős 1948). - Charles R Greathouse IV, Apr 17 2015
From Jianing Song, Apr 04 2022: (Start)
Burnside's p^a*q^b theorem says that a finite group whose order has at most 2 distinct prime factors is solvable, hence all terms have at least 3 distinct prime factors.
Terms not divisible by 12 are divisible by 320 and have at least 4 distinct prime factors (cf. A257391). (End)

Crossrefs

Subsequence of A000977 and A056868.

Programs

  • Mathematica
    ma[n_] := For[k = 1, True, k++, p = Prime[k]; m = 2^p*(2^(2*p) - 1); If[m > n, Return[False], If[Mod[n, m] == 0, Return[True]]]]; mb[n_] := For[k = 2, True, k++, p = Prime[k]; m = 3^p*((3^(2*p) - 1)/2); If[m > n, Return[False], If[Mod[n, m] == 0, Return[True]]]]; mc[n_] := For[k = 3, True, k++, p = Prime[k]; m = p*((p^2 - 1)/2); If[Mod[p^2 + 1, 5] == 0, If[m > n, Return[False], If[Mod[n, m] == 0, Return[True]]]]]; md[n_] := Mod[n, 2^4*3^3*13] == 0; me[n_] := For[k = 2, True, k++, p = Prime[k]; m = 2^(2*p)*(2^(2*p) + 1)*(2^p - 1); If[m > n, Return[False], If[Mod[n, m] == 0, Return[True]]]]; notSolvableQ[n_] := OddQ[n] || ma[n] || mb[n] || mc[n] || md[n] || me[n]; Select[ Range[3000], notSolvableQ] (* Jean-François Alcover, Jun 14 2012, from formula *)
  • PARI
    is(n)={
        if(n%5616==0,return(1));
        forprime(p=2,valuation(n,2),
            if(n%(4^p-1)==0, return(1))
        );
        forprime(p=3,valuation(n,3),
            if(n%(9^p\2)==0, return(1))
        );
        forprime(p=3,valuation(n,2)\2,
            if(n%((4^p+1)*(2^p-1))==0, return(1))
        );
        my(f=factor(n)[,1]);
        for(i=1,#f,
            if(f[i]>3 && f[i]%5>1 && f[i]%5<4 && n%(f[i]^2\2)==0, return(1))
        );
        0
    }; \\ Charles R Greathouse IV, Sep 11 2012

Formula

A positive integer k is a non-solvable number if and only if it is a multiple of any of the following numbers: a) 2^p*(2^(2*p)-1), p any prime. b) 3^p*(3^(2*p)-1)/2, p odd prime. c) p*(p^2-1)/2, p prime greater than 3 such that p^2 + 1 == 0 (mod 5). d) 2^4*3^3*13. e) 2^(2*p)*(2^(2*p)+1)*(2^p-1), p odd prime.

Extensions

More terms from Des MacHale, Feb 19 2001
Further terms from Francisco Salinas (franciscodesalinas(AT)hotmail.com), Dec 25 2001

A109379 Orders of non-cyclic simple groups (with repetition).

Original entry on oeis.org

60, 168, 360, 504, 660, 1092, 2448, 2520, 3420, 4080, 5616, 6048, 6072, 7800, 7920, 9828, 12180, 14880, 20160, 20160, 25308, 25920, 29120, 32736, 34440, 39732, 51888, 58800, 62400, 74412, 95040, 102660, 113460, 126000, 150348
Offset: 1

Views

Author

N. J. A. Sloane, Jul 29 2006

Keywords

Comments

The first repetition is at 20160 (= 8!/2) and the first proof that there exist two nonisomorphic simple groups of this order was given by the American mathematician Ida May Schottenfels (1869-1942). - David Callan, Nov 21 2006
By the Feit-Thompson theorem, all terms in this sequence are even. - Robin Jones, Dec 25 2023

References

  • See A001034 for references and other links.

Crossrefs

Cf. A001034 (orders without repetition), A119648 (orders that are repeated).

A131932 Number of nonisomorphic nonsolvable groups of order A056866(n).

Original entry on oeis.org

1, 3, 1, 1, 8, 1, 3, 6, 1, 26, 2, 2, 5, 2, 8, 23, 1, 6, 1, 107, 6, 1, 14, 1, 1, 1, 19, 2, 8, 28, 1, 93, 2, 4, 5, 5, 22, 1, 10, 1, 1, 588, 2, 20, 5, 1, 64, 4, 1, 5, 2, 5, 81, 1, 1, 18, 1, 25, 112, 2, 5, 1, 1
Offset: 1

Views

Author

Artur Jasinski, Jul 30 2007, Oct 20 2007

Keywords

Examples

			a(1) = 1 because there is only 1 nonsolvable group of order 60: A_5 (alternating group of 5th degree).
a(2) = 3 because there are 3 different nonsolvable groups of order 120.
		

Crossrefs

Programs

  • GAP
    NrUnsolvable := function(n) local i, count; count := 0; for i in [1..NumberSmallGroups(n)] do if not IsSolvableGroup(SmallGroup(n, i)) then count := count + 1; fi; od; return count; end; # Eric M. Schmidt, Apr 04 2013
    
  • GAP
    LoadPackage("GrpConst"); NrUnsolvable := function(n) local i, j, num; num := 0; for i in DivisorsInt(n) do if i<>1 then for j in [1..NrPerfectGroups(i)] do num := num + Length(Remove(UpwardsExtensions(PerfectGroup(IsPermGroup, i, j), n/i))); od; fi; od; return num; end; # Eric M. Schmidt, Nov 14 2013

Extensions

Edited by N. J. A. Sloane, Oct 08 2007
More terms from Eric M. Schmidt, Apr 04 2013
a(44)-a(63) from Eric M. Schmidt, Nov 14 2013

A340518 Smallest order of a finite group with a commutator subgroup of order n.

Original entry on oeis.org

1, 8, 6, 12, 10, 24, 14, 24, 18, 40, 22, 24, 26, 56, 30, 48, 34, 72, 38, 80, 42, 88, 46, 48, 50, 104, 54, 84, 58, 120, 62, 96, 66, 136, 70, 72, 74, 152, 78, 160, 82, 168, 86, 176, 90, 184, 94, 96, 98, 200, 102, 156, 106, 216, 110, 168, 114, 232
Offset: 1

Views

Author

Des MacHale, Jan 24 2021

Keywords

Comments

By Lagrange's Theorem a(n) is a multiple of n.
Are all terms after the first even?
The above conjecture is true. For even n, a(n) is even by Lagrange's theorem. For odd n, it follows from the fact that every dihedral group D_{2n} has a commutator subgroup of order n when n is odd; as no group of odd order is perfect, 2*n is the smallest possible order that such a commutator subgroup can be contained in. (For an extended proof see the Miles Englezou link.) - Miles Englezou, Mar 08 2024

Examples

			The fourth term is 12, because 12 is the smallest order of a group G with |G'| =  4, A_4 being an example.
		

Crossrefs

Programs

  • GAP
    # Produces a list A of the first 255 terms
    A:=[];
    N:=[1..255];
    F:=[1..20];     # for large n the array F may need to be extended beyond 20
    for n in N do
        for k in F do
        L:=List([1..NrSmallGroups(n*k)],i->Size(DerivedSubgroup(SmallGroup(n*k,i))));;
        if Positions(L,n)<>[] then
            Add(A,n*k);
            break;
        fi;
        od;
    od; # Miles Englezou, Feb 26 2024

Formula

a(2n+1) = 4n+2. - Miles Englezou, Mar 08 2024

Extensions

More terms from Miles Englezou, Feb 26 2024

A119648 Orders for which there is more than one simple group.

Original entry on oeis.org

20160, 4585351680, 228501000000000, 65784756654489600, 273457218604953600, 54025731402499584000, 3669292720793456064000, 122796979335906113871360, 6973279267500000000000000, 34426017123500213280276480
Offset: 1

Views

Author

N. J. A. Sloane, Jul 29 2006

Keywords

Comments

All such orders are composite numbers (since there is only one group of any prime order).
Orders which are repeated in A109379.
Except for the first number, these are the orders of symplectic groups C_n(q)=Sp_{2n}(q), where n>2 and q is a power of an odd prime number (q=3,5,7,9,11,...). Also these are the orders of orthogonal groups B_n(q). - Dushan Pagon (dushanpag(AT)gmail.com), Jun 27 2010
a(1) = 20160 = 8!/2 is the order of the alternating simple group A_8 that is isomorphic to the Lie group PSL_4(2), but 20160 is also the order of the Lie group PSL_3(4) that is not isomorphic to A_8 (see A137863). - Bernard Schott, May 18 2020

Examples

			From Dushan Pagon (dushanpag(AT)gmail.com), Jun 27 2010: (Start)
a(1)=|A_8|=8!/2=20160,
a(2)=|C_3(3)|=4585351680,
a(3)=|C_3(5)|=228501000000000, and
a(4)=|C_4(3)|=65784756654489600. (End)
		

References

  • See A001034 for references and other links.
  • J. H. Conway, R. T. Curtis, S. P. Norton, R. A. Parker and R. A. Wilson, ATLAS of Finite Groups. Oxford Univ. Press, 1985 [for best online version see https://oeis.org/wiki/Welcome#Links_to_Other_Sites]. [From Dushan Pagon (dushanpag(AT)gmail.com), Jun 27 2010]

Crossrefs

Cf. A001034 (orders of simple groups without repetition), A109379 (orders with repetition), A137863 (orders of simple groups which are non-cyclic and non-alternating).

Programs

  • Other
    sp(n, q) 1/2 q^n^2.(q^(2.i) - 1, i, 1, n) [From Dushan Pagon (dushanpag(AT)gmail.com), Jun 27 2010] [This line contained some nonascii characters which were unreadable]

Formula

For n>1, a(n) is obtained as (1/2) q^(m^2)Prod(q^(2i)-1, i=1..m) for appropriate m>2 and q equal to a power of some odd prime number. [Dushan Pagon (dushanpag(AT)gmail.com), Jun 27 2010]

Extensions

Extended up to the 10th term by Dushan Pagon (dushanpag(AT)gmail.com), Jun 27 2010

A131933 a(n) = A056866(n)/4.

Original entry on oeis.org

15, 30, 42, 45, 60, 75, 84, 90, 105, 120, 126, 135, 150, 165, 168, 180, 195, 210, 225, 240, 252, 255, 270, 273, 285, 294, 300, 315, 330, 336, 345, 360, 375, 378, 390, 405, 420, 435, 450, 462, 465, 480, 495, 504, 510, 525, 540, 546, 555, 570, 585, 588, 600, 612
Offset: 1

Views

Author

Artur Jasinski, Jul 30 2007

Keywords

Comments

All orders of nonsolvable groups A056866 are divisible by 4.

Crossrefs

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