Entringer Number
The Entringer numbers 
are the number of Permutations of 
, starting with
, which, after initially falling, alternately fall then rise. The Entringer numbers are given by
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together with the Recurrence Relation
The numbers
are the Secant and Tangent Numbers given by theMaclaurin Series
See also Alternating Permutation, Boustrophedon Transform, Euler Zigzag Number, Permutation,Secant Number, Seidel-Entringer-Arnold Triangle, Tangent Number, Zag Number, Zig Number
References
Entringer, R. C. ``A Combinatorial Interpretation of the Euler and Bernoulli Numbers.'' Nieuw. Arch. Wisk. 14, 241-246, 1966. Millar, J.; Sloane, N. J. A.; and Young, N. E. ``A New Operation on Sequences: The Boustrophedon Transform.'' J. Combin. Th. Ser. A 76, 44-54, 1996. Poupard, C. ``De nouvelles significations enumeratives des nombres d'Entringer.'' Disc. Math. 38, 265-271, 1982.
- Triangle Transformation Principle
- Triangular Cupola
- Triangular Dipyramid
- Triangular Graph
- Triangular Hebesphenorotunda
- Triangular Matrix
- Triangular Number
- Triangular Orthobicupola
- Triangular Pyramid
- Triangular Square Number
- Triangular Symmetry Group
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- Triaugmented Dodecahedron
- Triaugmented Hexagonal Prism
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- Triaxial Ellipsoid
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