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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
 1, 1, 0, 1, 8, 22, 51, 342, 2609, 16896, 99114, 876579, 8551800, 79595269, 764804085, 8905825760 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS Huff paper has a typographical error, a(8)=2669. - Sean A. Irvine, Dec 14 2014 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). R. Spira, Noncomplete residue systems, Problem 71-4, SIAM Rev., 14 (1972), 173ff. LINKS G. B. Huff, On pairings of the first 2n natural numbers, Acta Arithmetica, 23 (1973), 117-126. D. A. Klarner, Letter to N. J. A. Sloane, Mar 1974 R. Spira, Noncomplete residue system Problem 71-4, SIAM Rev., 14 (1972), 173-174. (Annotated scanned copy) CROSSREFS Cf. A007631. Sequence in context: A305181 A048489 A124701 * A211530 A058404 A211479 Adjacent sequences:  A002965 A002966 A002967 * A002969 A002970 A002971 KEYWORD nonn,more AUTHOR EXTENSIONS Better definition and values of a(11)-a(15) from Sean A. Irvine, Dec 14 2014 a(0)=1 prepended by Alois P. Heinz, Oct 05 2018 STATUS approved

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Last modified April 14 07:59 EDT 2021. Contains 342946 sequences. (Running on oeis4.)