A007499 Number of cases considered in a particular algorithm for enumerating hexaflexagrams.

2, 3, 4, 12, 20, 55, 127, 371, 1037, 3249, 10071, 32913, 108112, 363618, 1233938, 4244102, 14716095, 51480027, 181312939

Offset: 1

Author

N. J. A. Sloane, Robert G. Wilson v, circa 1976

Keywords

• nonn
• more

Comments

See O'Reilly reference for precise definition.

References

• Thomas J. O'Reilly, Classifying and Counting Hexaflexagrams, J. Rec. Math., 8 (1976), 182-187.
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Sean A. Irvine, Java program (github)
• Thomas J. O'Reilly, Classifying and Counting Hexaflexagrams, J. Rec. Math., 8 (1976), 182-187. [Annotated scanned copy]

Crossrefs

Cf. A000207.

Extensions

Title clarified and a(11)-a(19) from Sean A. Irvine, Jul 12 2022