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A214271 Number of compositions of n where the difference between largest and smallest parts equals 2 and adjacent parts are unequal. 2
0, 2, 1, 8, 7, 13, 25, 27, 43, 71, 85, 124, 186, 260, 346, 509, 716, 1002, 1434, 1989, 2829, 4051, 5693, 8043, 11459, 16240, 23028, 32780, 46497, 66031, 93930, 133527, 189826, 270137, 384082, 546262, 777617, 1106381, 1574318, 2240820, 3189344, 4539451, 6462231 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 3..5000

FORMULA

a(n) ~ c * d^n, where d = 1.42405422074094158891999182454432643651250048913477... is the root of the equation d^5 - d^4 + d^3 - 2*d^2 + d - 2 = 0 and c = 0.7949863587395197228140209096861039705690343740923239... - Vaclav Kotesovec, May 01 2014

EXAMPLE

a(4) = 2: [3,1], [1,3].

a(5) = 1: [1,3,1].

a(6) = 8: [4,2], [3,2,1], [3,1,2], [2,4], [2,3,1], [2,1,3], [1,3,2], [1,2,3].

a(7) = 7: [3,1,3], [3,1,2,1], [2,1,3,1], [1,3,2,1], [1,3,1,2], [1,2,3,1], [1,2,1,3].

a(8) = 13: [5,3], [3,5], [3,2,1,2], [3,1,3,1], [2,4,2], [2,3,2,1], [2,3,1,2], [2,1,3,2], [2,1,2,3], [1,3,1,3], [1,3,1,2,1], [1,2,3,2], [1,2,1,3,1].

CROSSREFS

Column k=2 of A214269.

Sequence in context: A254180 A248052 A105672 * A262007 A005489 A015152

Adjacent sequences:  A214268 A214269 A214270 * A214272 A214273 A214274

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Jul 09 2012

STATUS

approved

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Last modified September 22 07:34 EDT 2020. Contains 337289 sequences. (Running on oeis4.)