A375209 - OEIS

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A375209

Number of simple symmetric Hamiltonian paths connecting opposite corners of a 2n+1 X 2n+1 grid.

1

1, 2, 16, 564, 93866, 72054120, 260324223938, 4400423201461008, 349815282628284276844, 130501147375292529852604266, 228964256366276749773274186140858

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..10.

Nicolay Avilov, Problem 2718. Broken Routes (in Russian).

Nicolay Avilov, Illustration for term a(2)

FORMULA

a(n) = 2*A331001(2*n + 1) for n > 0. - Andrew Howroyd, Oct 16 2024

EXAMPLE

a(2) = 16, see link "Illustration".

CROSSREFS

Cf. A001184, A331001.

Sequence in context: A012679 A012726 A013177 * A060279 A369674 A012757

Adjacent sequences: A375204 A375206 A375207 * A375212 A375213 A375214

KEYWORD

nonn,more,new

AUTHOR

Nicolay Avilov, Oct 16 2024

EXTENSIONS

Thanks to Suleiman Makarenko.

a(5)-a(10) from Andrew Howroyd, Oct 16 2024

STATUS

approved