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 A332651 Number of polygonal cacti on n unlabeled nodes with every polygon having an even number of edges. 3
 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 4, 2, 7, 9, 14, 26, 48, 71, 154, 243, 478, 894, 1631, 3149, 6062, 11295, 22469, 42900, 83528, 164829, 321012, 632960, 1255613, 2472803, 4928140, 9808439, 19533534, 39134059, 78345317, 157177556, 316398963, 636790282, 1284910954 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,11 COMMENTS Bridges are disallowed. LINKS Andrew Howroyd, Table of n, a(n) for n = 0..200 Wikipedia, Cactus graph EXAMPLE a(6) = 1 corresponding with a hexagon. a(7) = 1 corresponding with two quadrilaterals joined at a node. PROG (PARI) \\ See A332650 for UCacti. seq(n)={concat([1], UCacti(vector(n, i, i>2&&i%2==0)))} CROSSREFS Cf. A000083, A035085, A091487, A332649, A332650. Sequence in context: A203575 A120871 A019689 * A072009 A257502 A201207 Adjacent sequences:  A332648 A332649 A332650 * A332652 A332653 A332654 KEYWORD nonn AUTHOR Andrew Howroyd, Feb 18 2020 STATUS approved

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Last modified April 11 22:01 EDT 2021. Contains 342888 sequences. (Running on oeis4.)