A007822 - OEIS

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A007822

Number of symmetric foldings of 2n+1 stamps.

1, 1, 3, 9, 28, 89, 287, 935, 3072, 10157, 33767, 112736, 377836, 1270203, 4282311, 14470629, 49005732, 166261653, 565055147, 1923186472, 6554868916, 22367933148, 76417819396, 261335128098, 894597454360, 3064970675173

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..26.

J. E. Koehler, Folding a strip of stamps, J. Combin. Theory, 5 (1968), 135-152.

Stéphane Legendre, Illustration of initial terms

S. Legendre, Foldings and Meanders, arXiv preprint arXiv:1302.2025, 2013.

S. Legendre, Foldings and Meanders, Aust. J. Comb. 58(2), 275-291, 2014.

W. F. Lunnon, A map-folding problem, Math. Comp. 22 (1968), 193-199.

Index entries for sequences obtained by enumerating foldings

CROSSREFS

Cf. A001010.

Sequence in context: A199104 A049220 A094790 * A094164 A094803 A094826

Adjacent sequences: A007819 A007820 A007821 * A007823 A007824 A007825

KEYWORD

nonn

AUTHOR

Stéphane Legendre

EXTENSIONS

More terms from Stéphane Legendre (2013) added by N. J. A. Sloane, Mar 30 2013

STATUS

approved