A135909 Clique number of commuting graph of alternating group A_n.

0, 0, 0, 2, 3, 4, 8, 11, 15, 26, 35, 47, 80, 107, 143, 242, 323, 431, 728, 971, 1295, 2186, 2915, 3887, 6560, 8747, 11663, 19682, 26243, 34991, 59048, 78731, 104975, 177146, 236195, 314927, 531440, 708587, 944783, 1594322, 2125763, 2834351, 4782968, 6377291, 8503055, 14348906

Offset

0,4

Comments

The graph is empty for n = 0, 1 and 2, so a(n) = 0 by convention (or should it be 1?).

References

A. Iranmanesh and A. Jafarzadeh, On the commuting graph associated with the symmetric and alternating groups, J. Algebra and Applic., 7 (2008), 129-146.

Links

Table of n, a(n) for n=0..45.

Formula

Conjecture: a(n) = a(n-1)+3*a(n-3)-3*a(n-4) for n>6. G.f.: -x^3*(x^6-x^5+2*x^3-x^2-x-2) / ((x-1)*(3*x^3-1)). - Colin Barker, Jul 26 2013

Crossrefs

Sequence in context: A295323 A102951 A015935 * A046812 A269797 A280195

Adjacent sequences: A135906 A135907 A135908 * A135910 A135911 A135912

Keyword

nonn

Author

N. J. A. Sloane, Mar 07 2008

Status

approved