A005441 Number of isonemal fabrics of period exactly n. (Formerly M3230)

1, 1, 4, 4, 9, 8, 55, 21, 104, 62, 429, 196, 800, 698, 4674, 2070, 7721, 7154

Offset

2,3

References

B. Grünbaum and G. C. Shephard, The geometry of fabrics, pp. 77-97 of F. C. Holroyd and R. J. Wilson, editors, Geometrical Combinatorics. Pitman, Boston, 1984. [gives different a(10) which is probably erroneous]

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Table of n, a(n) for n=2..19.

Branko Grünbaum and G. C. Shephard, A catalogue of isonemal fabrics, Discrete Geometry and Convexity, 440 (1985), 279-298.

B. Grünbaum and G. C. Shephard, An extension to the catalogue of isonemal fabrics, Discrete Mathematics, 60, (1986), 155-192.

Formula

a(n) = A000046(n) + A193140(n) + A262589(n).

Crossrefs

Cf. A000046, A193140, A262589.

Sequence in context: A049723 A010661 A051668 * A362294 A198497 A231980

Adjacent sequences: A005438 A005439 A005440 * A005442 A005443 A005444

Keyword

nonn,more

Author

Simon Plouffe

Extensions

a(14)-a(19) from second Grünbaum and Shephard paper added by Sean A. Irvine, Jun 26 2016

a(10) corrected by Andrey Zabolotskiy, Apr 14 2023

Status

approved