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 A053517 Number of connected directed 2-multigraphs on n nodes. 1
 1, 5, 132, 22662, 29174514, 286151774704, 21712410740238954, 12980058344488389640470, 62082372574276838787463958455, 2405193558246444686967534052419452898, 762399004073792344564641131264446658930745417 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A 2-multigraph is similar to an ordinary graph except there are 0, 1 or 2 edges between any two nodes (self-loops are not allowed). LINKS Andrew Howroyd, Table of n, a(n) for n = 1..40 FORMULA Inverse Euler transform of A053467. CROSSREFS Cf. A053467. Sequence in context: A187357 A135758 A152794 * A296191 A114474 A280305 Adjacent sequences:  A053514 A053515 A053516 * A053518 A053519 A053520 KEYWORD easy,nonn AUTHOR Vladeta Jovovic, Jan 14 2000 EXTENSIONS a(11) from Andrew Howroyd, Nov 07 2019 STATUS approved

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Last modified December 9 19:51 EST 2019. Contains 329879 sequences. (Running on oeis4.)