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A236755 Number of irregular spiral (expanded spiral) appearing with n center points. 1
0, 2, 0, 16, 0, 720, 0, 35712, 0, 3628800, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See A236535 for construction rule.

Conjecture: (1) For even n; except n mod 4 = 0; all forms are expanded spirals and equal to n!. (2) For n mod 4 = 0, there are both non-expanded loops and expanded spirals.

LINKS

Table of n, a(n) for n=1..11.

Kival Ngaokrajang, Illustration of irregular spirals, center points = 1..6

Kival Ngaokrajang, Small Basic program

CROSSREFS

Cf. A014105 (2 center points); A234902, A234903, A234904, A236535 (3 center points); A235088, A235089 (4 center points); A236326, A236327 (5 center  points).

Sequence in context: A025600 A009006 A155585 * A057375 A009045 A060313

Adjacent sequences:  A236752 A236753 A236754 * A236756 A236757 A236758

KEYWORD

nonn,more

AUTHOR

Kival Ngaokrajang, Jan 30 2014

STATUS

approved

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Last modified February 20 10:56 EST 2018. Contains 299385 sequences. (Running on oeis4.)