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%I #8 May 12 2020 19:56:37
%S 0,2,15,64,220,672,1904,5120,13248,33280,81664,196608,465920,1089536,
%T 2519040,5767168,13090816,29491200,65994752,146800640,324796416,
%U 715128832,1567621120,3422552064,7444889600,16139681792,34879832064,75161927680,161531035648,346281738240
%N Number of singly defective permutations of 1..n with exactly 1 maximum.
%C A singly defective permutation omits one value and repeats another value.
%C a(1) is zero because there are no defective permutations of a single element.
%H Andrew Howroyd, <a href="/A183264/b183264.txt">Table of n, a(n) for n = 1..500</a>
%F Conjecture: a(n) = n * (3*n-4) * 2^(n-3) for n > 1. - _Andrew Howroyd_, May 12 2020
%e Some solutions for n=3 with 1 maximum:
%e (3,3,2) (1,3,3) (1,1,2) (2,1,1) (3,3,1) (1,3,1) (1,2,2) (2,2,1) (2,2,3).
%Y Column 1 of A183270.
%Y Cf. A053220.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 03 2011
%E Terms a(16) and beyond from _Andrew Howroyd_, May 12 2020
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