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A130131 Number of n-lobsters. 5
1, 1, 1, 2, 3, 6, 11, 23, 47, 105, 231, 532, 1224, 2872, 6739, 15955, 37776, 89779, 213381, 507949, 1209184, 2880382, 6861351, 16348887, 38955354, 92831577, 221219963, 527197861, 1256385522, 2994200524, 7135736613, 17005929485 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..200

Andrew Howroyd, Formula for number of lobsters

G. Li and F. Ruskey, C program

Eric Weisstein's World of Mathematics, Lobster Graph

PROG

(PARI)

s(n)={my(ox=O(x^n)); x^2*((1/eta(x+ox)-1/(1-x))^2/(1-x/eta(x+ox)) + (1/eta(x^2+ox)-1/(1-x^2))*(1+x/eta(x+ox))/(1-x^2/eta(x^2+ox)))/2 + x/eta(x+ox) - x^3/((1-x)^2*(1+x))}

Vec(s(30)) \\ Andrew Howroyd, Nov 02 2017

CROSSREFS

Cf. A000055, A058984, A130132.

Sequence in context: A198648 A198655 A211694 * A277796 A123465 A000055

Adjacent sequences:  A130128 A130129 A130130 * A130132 A130133 A130134

KEYWORD

nonn

AUTHOR

Eric W. Weisstein, May 11 2007

EXTENSIONS

a(15)-a(32) from Washington Bomfim, Feb 23 2011

STATUS

approved

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Last modified February 20 01:17 EST 2018. Contains 299357 sequences. (Running on oeis4.)