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A054952 Number of unlabeled semi-strong digraphs on n nodes with pairwise different components. 4

%I #25 Jan 14 2022 23:19:34

%S 1,1,6,88,5136,1052154,706474926,1581054875274,12140605885784816,

%T 328173091958855376334,31831409045512513121561226,

%U 11234306828778006073392046869300,14576263867446651299709243211339018934,70075728362101598938266196294267261948879446

%N Number of unlabeled semi-strong digraphs on n nodes with pairwise different components.

%C Weigh transform of A035512. - _Andrew Howroyd_, Sep 10 2018

%C A digraph is semi-strong if all its weakly connected components are strongly connected. - _Andrew Howroyd_, Jan 14 2022

%H Andrew Howroyd, <a href="/A054952/b054952.txt">Table of n, a(n) for n = 1..50</a>

%H V. A. Liskovets, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL3/LISK/Derseq.html">Some easily derivable sequences</a>, J. Integer Sequences, 3 (2000), #00.2.2.

%F G.f.: -1 + Product_{n > 0} (1 + x^n)^A035512(n). - _Andrew Howroyd_, Sep 10 2018

%t m = 15;

%t A035512 = Cases[Import["https://oeis.org/A035512/b035512.txt", "Table"], {_, _}][[All, 2]];

%t gf = -1 + Product[(1 + x^n)^A035512[[n + 1]], {n, 1, m}];

%t CoefficientList[gf + O[x]^m , x] // Rest (* _Jean-François Alcover_, Aug 26 2019, after _Andrew Howroyd_ *)

%Y Cf. A035512, A054951, A054953, A054954.

%K nonn,easy

%O 1,3

%A _N. J. A. Sloane_, May 24 2000

%E More terms from _Vladeta Jovovic_, Mar 11 2003

%E a(12)-a(14) from _Andrew Howroyd_, Sep 10 2018

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Last modified April 19 02:45 EDT 2024. Contains 371782 sequences. (Running on oeis4.)