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A001415 Number of ways of folding a 2 X n strip of stamps.
(Formerly M1891 N0745)
0
1, 2, 8, 60, 320, 1980, 10512, 60788, 320896, 1787904, 9381840, 51081844, 266680992, 1429703548, 7432424160, 39409195740, 204150606976, 1073644675448, 5545305620064 (list; graph; refs; listen; history; text; internal format)
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..18.

R. Dickau, Map Folding

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

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 A053871 A208124

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

STATUS

approved

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Last modified January 21 18:10 EST 2019. Contains 319350 sequences. (Running on oeis4.)