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A223093
Number of foldings of n labeled stamps in which leaf 1 is inwards and leaf n outwards (or leaf 1 outwards and leaf n inwards).
3
0, 0, 2, 4, 16, 38, 132, 342, 1144, 3134, 10370, 29526, 97458, 285458, 942920, 2822310, 9341008, 28440970, 94358558, 291294678, 968853072, 3025232480, 10086634316, 31797822936, 106265437078, 337731551446, 1131117792978, 3620119437762, 12148796744234, 39118879440938
OFFSET
1,3
COMMENTS
Subset of foldings of n labeled stamps (A000136). - Stéphane Legendre, Apr 09 2013
LINKS
Stéphane Legendre, Table of n, a(n) for n = 1..42
S. Legendre, Foldings and Meanders, arXiv preprint arXiv:1302.2025 [math.CO], 2013.
S. Legendre, Foldings and Meanders, Aust. J. Comb. 58(2), 275-291, 2014.
FORMULA
a(n) = A000682(n+1) - A077014(n). - Andrew Howroyd, Dec 06 2015
A217310(n) = 2*a(n) if n is odd and A217310(n) = a(n) if n is even. - Stéphane Legendre, Jan 09 2014
MATHEMATICA
A000682 = Cases[Import["https://oeis.org/A000682/b000682.txt", "Table"], {_, _}][[All, 2]];
A077014 = Cases[Import["https://oeis.org/A077014/b077014.txt", "Table"], {_, _}][[All, 2]];
a[n_] := A000682[[n + 1]] - A077014[[n + 1]];
Array[a, 30] (* Jean-François Alcover, Sep 07 2019, after Andrew Howroyd *)
CROSSREFS
Sequence in context: A051861 A296297 A290265 * A333022 A048222 A192890
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 29 2013
EXTENSIONS
Name clarified by Stéphane Legendre, Apr 09 2013
More terms from Stéphane Legendre, Apr 09 2013
STATUS
approved