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%I #18 Feb 26 2018 08:08:04
%S 2,55,389,1563,4642,11407,24600,48204,87758,150707,246787,388445,
%T 591294,874603,1261822,1781142,2466090,3356159,4497473,5943487,
%U 7755722,10004535,12769924,16142368,20223702,25128027,30982655,37929089,46124038,55740467
%N Number of permutations that are 3 "block reversals" away from 12...n.
%Y Cf. A007972, A007973, A007974.
%Y Column k=3 of A300003.
%K nonn
%O 4,1
%A _J. H. Conway_
%E More terms from _Sean A. Irvine_, Feb 22 2018