A001010 - OEIS

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A001010

Number of symmetric foldings of a strip of n stamps.
(Formerly M0323 N0120)

1, 2, 2, 4, 6, 8, 18, 20, 56, 48, 178, 132, 574, 348, 1870, 1008, 6144, 2812, 20314, 8420, 67534, 24396, 225472, 74756, 755672, 222556, 2540406, 693692, 8564622, 2107748, 28941258, 6656376, 98011464, 20548932

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

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

Jean-François Alcover, Table of n, a(n) for n = 1..52

R. Dickau, Symmetric Stamp Foldings

R. Dickau, Symmetric Stamp Foldings [Cached copy, pdf format, with permission]

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

J. E. Koehler, Folding a strip of stamps, J. Combin. Theory, 5 (1968), 135-152. [Annotated, corrected, scanned copy]

Frank Ruskey, Information on Stamp Foldings

Eric Weisstein's World of Mathematics, Stamp Folding.

Index entries for sequences obtained by enumerating foldings

FORMULA

a(2n) = 2*A000682(n+2), a(2n+1) = 2*A007822(n). - Sean A. Irvine, Mar 18 2013

MATHEMATICA

A000682 = Import["https://oeis.org/A000682/b000682.txt", "Table"][[All, 2]];

A007822 = Cases[Import["https://oeis.org/A007822/b007822.txt", "Table"], {_, _}][[All, 2]];

a[n_] := Which[n == 1, 1, EvenQ[n], 2*A000682[[n/2 + 1]], OddQ[n], 2*A007822[[(n - 1)/2 + 1]]];

Array[a, 52] (* Jean-François Alcover, Sep 03 2019, updated Jul 13 2022 *)

CROSSREFS

Cf. A007822, A000682.

Sequence in context: A216214 A269298 A153964 * A357952 A091966 A231187

Adjacent sequences: A001007 A001008 A001009 * A001011 A001012 A001013

KEYWORD

nonn,nice

AUTHOR

N. J. A. Sloane, Stéphane Legendre

STATUS

approved