A236754 Number of irregular spirals (non-expanded loop) appearing with n center points.

1, 0, 6, 8, 120, 0, 5040, 4608, 362880, 0, 39916800

Offset

1,3

Comments

See A236535 for construction rule.

Conjecture: (1) For odd n all forms are non-expanded loops 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: A013240 A161801 A211041 * A069660 A119001 A324987

Adjacent sequences: A236751 A236752 A236753 * A236755 A236756 A236757

Keyword

nonn,more

Author

Kival Ngaokrajang, Jan 30 2014

Status

approved