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A320499
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Number of connected self-dual signed graphs with n nodes.
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2
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1, 1, 0, 1, 3, 14, 62, 572, 7409, 163284, 5736443, 342169618, 33534945769, 5442700283638, 1484664946343496, 664513607618098252, 508538464299389501337, 635542752091150346032474, 1374528064543283977151585962, 4842758246111267151697826493193
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listen;
history;
text;
internal format)
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OFFSET
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0,5
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LINKS
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FORMULA
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a(2*n-1) = b(2*n-1), a(2*n) = b(2*n) - (A053465(n) - a(n))/2 where b is the Inverse Euler transform of A004104. - Andrew Howroyd, Jan 27 2020
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PROG
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(PARI) \\ See link for program.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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a(0)=1 prepended and terms a(13) and beyond from Andrew Howroyd, Jan 26 2020
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STATUS
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approved
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