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 A002968 Number of pairings {(b[1],c[1]),(b[2],c[2]),...,(b[n],c[n])} of the first 2n positive integers satisfying b[i] < c[i] and such that the 2n numbers c[i]+b[i] and c[i]-b[i] are all distinct. (Formerly M4494) 6

%I M4494

%S 1,1,0,1,8,22,51,342,2609,16896,99114,876579,8551800,79595269,

%T 764804085,8905825760

%N Number of pairings {(b[1],c[1]),(b[2],c[2]),...,(b[n],c[n])} of the first 2n positive integers satisfying b[i] < c[i] and such that the 2n numbers c[i]+b[i] and c[i]-b[i] are all distinct.

%C Huff paper has a typographical error, a(8)=2669. - _Sean A. Irvine_, Dec 14 2014

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%D R. Spira, Noncomplete residue systems, Problem 71-4, SIAM Rev., 14 (1972), 173ff.

%H R. K. Guy, <a href="/A002968/a002968_1.pdf">Letter to G. B. Huff & N. J. A. Sloane, Aug 1974</a>

%H G. B. Huff, <a href="http://matwbn.icm.edu.pl/ksiazki/aa/aa23/aa2322.pdf">On pairings of the first 2n natural numbers</a>, Acta Arithmetica, 23 (1973), 117-126.

%H D. A. Klarner, <a href="/A002968/a002968.pdf">Letter to N. J. A. Sloane, Mar 1974</a>

%H R. Spira, <a href="/A002968/a002968_2.pdf">Noncomplete residue system Problem 71-4</a>, SIAM Rev., 14 (1972), 173-174. (Annotated scanned copy)

%Y Cf. A007631.

%K nonn,more

%O 0,5

%A _N. J. A. Sloane_.

%E Better definition and values of a(11)-a(15) from _Sean A. Irvine_, Dec 14 2014

%E a(0)=1 prepended by _Alois P. Heinz_, Oct 05 2018

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Last modified January 27 15:14 EST 2020. Contains 331295 sequences. (Running on oeis4.)