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Number of disconnected regular simple graphs on n vertices with girth at least 4.
17

%I #17 May 01 2014 02:37:07

%S 0,0,1,1,2,1,2,1,3,2,4,3,7,5,10,8,22,12,54,20,218,62,1436,1731,27810,

%T 197981,2613814,33117962,463707741,6709514340,102306352539,

%U 1597440872801

%N Number of disconnected regular simple graphs on n vertices with girth at least 4.

%H Jason Kimberley, <a href="/wiki/User:Jason_Kimberley/D_k-reg_girth_ge_g_index">Index of sequences counting disconnected k-regular simple graphs with girth at least g</a>

%Y This sequence is the row sum sequence of A185204.

%Y Regular graphs, of any degree, with girth at least 4: A186724 (connected), this sequence (disconnected), A185314 (not necessarily connected).

%Y Disconnected k-regular simple graphs with girth at least 4: this sequence (any k), A185204 (triangle); specified degree k: A185224 (k=2), A185234 (k=3), A185244 (k=4), A185254 (k=5), A185264 (k=6), A185274 (k=7), A185284 (k=8), A185294 (k=9).

%K nonn,more,hard

%O 0,5

%A _Jason Kimberley_, Mar 26 2012

%E a(31) corrected by the author, propagated from A185244, Jan 05 2013