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 A208962 Number of n-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero and first and second differences in -n..n. 0
 1, 1, 2, 8, 40, 495, 7425, 140429, 3014206, 73238115, 2000005946 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Diagonal of A208970. LINKS EXAMPLE Some solutions for n=5: .-2...-3...-3...-1...-2...-1...-1...-2...-2...-1...-2....0...-2...-2...-3...-3 .-2...-3...-1....0...-1....0...-1...-1....0....0...-1....0....0....0...-2...-3 ..1....2....1...-1....2....0....1....2....2...-1....1....0....0....1....3....1 ..1....2....3....0....0....0....0....1...-1....1....2....0....1....0....3....3 ..2....2....0....2....1....1....1....0....1....1....0....0....1....1...-1....2 CROSSREFS Sequence in context: A111394 A140363 A280921 * A351109 A012597 A012534 Adjacent sequences: A208959 A208960 A208961 * A208963 A208964 A208965 KEYWORD nonn AUTHOR R. H. Hardin, Mar 03 2012 STATUS approved

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Last modified December 8 14:51 EST 2022. Contains 358695 sequences. (Running on oeis4.)