A001415 Number of ways of folding a 2 X n strip of stamps. (Formerly M1891 N0745)

1, 2, 8, 60, 320, 1980, 10512, 60788, 320896, 1787904, 9381840, 51081844, 266680992, 1429703548, 7432424160, 39409195740, 204150606976, 1073644675448, 5545305620064, 28980175671212, 149302889205120

Offset

0,2

Comments

a(n), called G(n,2), is known to be divisible by 4n for n >= 2. - Fred Lunnon, Dec 08 2013

References

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

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=0..20.

Robert Dickau, Map Folding

Robert Dickau, Folding a 2xn Sheet of Labeled Stamps, Wolfram Demonstrations Project

Hunter Hogan, mapFolding: A computational framework for enumerating distinct folding patterns of rectangular maps, GitHub repository, (2025).

W. F. Lunnon, Multi-dimensional map-folding, Computer Journal 14 1971 75-80.

Eric Weisstein's World of Mathematics, Map Folding

Index entries for sequences obtained by enumerating foldings

Crossrefs

Sequence in context: A295502 A196076 A027278 * A305730 A364077 A053871

Adjacent sequences: A001412 A001413 A001414 * A001416 A001417 A001418

Keyword

nonn,more

Author

N. J. A. Sloane

Extensions

a(12)-a(18) from Fred Lunnon, Dec 08 2013

a(19)-a(20) from Hunter Hogan, Mar 21 2025

Status

approved