A019438 Squarefree orders of elements of Mathieu group M_23.

1, 2, 3, 5, 6, 7, 11, 14, 15, 23

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• fini
• full

Comments

Numbers having a unique partition into four nonnegative squares. Let r=2, 6, or 14. Then the numbers r*4^k also have unique partitions into the four nonnegative squares for k>0. See A006431. - T. D. Noe, Aug 10 2005

Links

• D. H. Lehmer, On the Partition of Numbers into Squares, The American Mathematical Monthly, Vol. 55, No.8, October 1948, pp. 476-481.
• G. Nebe and M. Teider, Hecke actions on certain strongly modular genera of lattices, Archiv der Mathematik 84 (1) (2005) 46-56.
• E. M. Rains and N. J. A. Sloane, The Shadow Theory of Modular and Unimodular Lattices, J. Number Theory, 73 (1998), 359-389.