OFFSET
1,1
LINKS
Jorge R. F. F. Lopes, Table of n, a(n) for n = 1..10000 (terms 1..369 from Muniru A Asiru).
H. U. Besche, B. Eick and E. A. O'Brien, The Small Groups Library
Gordon Royle, Numbers of Small Groups
FORMULA
Sequence is { m | A000001(m) = 4 }. - Muniru A Asiru, Nov 04 2017
EXAMPLE
For m = 28, the 4 groups of order 8 are C7 : C4, C28, D28, C14 x C2 and for m = 30 the 4 groups of order 30 are C5 x S3, C3 x D10, D30, C30 where C, D mean cyclic, dihedral groups of the stated order and S is the symmetric group of the stated degree. The symbols x and : mean direct and semidirect products respectively. - Muniru A Asiru, Nov 04 2017
MATHEMATICA
Select[Range[500], FiniteGroupCount[#] == 4 &] (* Jean-François Alcover, Dec 08 2017 *)
PROG
(GAP) A054396 := Filtered([1..2015], n -> NumberSmallGroups(n) = 4); # Muniru A Asiru, Nov 04 2017
CROSSREFS
Cf. A000001. Cyclic numbers A003277. Numbers m such that there are precisely k groups of order m: A054395 (k=2), A055561 (k=3), this sequence (k=4), A054397 (k=5), A135850 (k=6), A249550 (k=7), A249551 (k=8), A249552 (k=9), A249553 (k=10), A249554 (k=11), A249555 (k=12), A292896 (k=13), A294155 (k=14), A294156 (k=15), A295161 (k=16), A294949 (k=17), A298909 (k=18), A298910 (k=19), A298911 (k=20).
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, May 21 2000
EXTENSIONS
More terms from Christian G. Bower, May 25 2000
STATUS
approved