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A318590 Number of connected balanced signed graphs on n unlabeled nodes. 3
1, 1, 2, 5, 28, 177, 1982, 33997, 1020516, 54570672, 5347070228, 967135763525, 324200029119318, 202046821340636691, 234878262433630160622, 511060736355598412146405, 2088401066728281847415734793, 16079824271822965645002329491423, 233994776259866281916838227225733732 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..50

Wikipedia, Signed graph

FORMULA

a(2*n+1) = A054921(2*n+1)/2, a(2*n) = (a(n) + A054919(n) + A054921(2*n) - A054921(n))/2.

Inverse Euler transform of A034892.

CROSSREFS

Cf. A005142, A034892, A053465, A054919, A054921.

Sequence in context: A095159 A047132 A264699 * A072371 A019043 A009635

Adjacent sequences:  A318587 A318588 A318589 * A318591 A318592 A318593

KEYWORD

nonn

AUTHOR

Andrew Howroyd, Sep 25 2018

STATUS

approved

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Last modified May 19 22:32 EDT 2019. Contains 323411 sequences. (Running on oeis4.)