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A188225 Number of ways to select 15 knights from n knights sitting at a round table if no adjacent knights are chosen. 0
2, 31, 256, 1496, 6936, 27132, 93024, 286824, 810084, 2124694, 5230016, 12183560, 27041560, 57500460, 117675360, 232676280, 445962870, 830905245, 1508593920, 2674776720, 4639918800, 7887861960, 13160496960, 21578373360, 34810394760 (list; graph; refs; listen; history; text; internal format)
OFFSET

30,1

LINKS

Table of n, a(n) for n=30..54.

FORMULA

a(n) = C(n - 15, 15) + C(n - 16, 14)

EXAMPLE

For n = 30 a(30) = C(15, 15) + C(14, 14) = 2

MATHEMATICA

Table[Binomial[n-15, 15]+Binomial[n-16, 14], {n, 30, 60}] (* Harvey P. Dale, May 16 2018 *)

CROSSREFS

a(n) = A010968(n - 15) + A010967(n - 16)

Sequence in context: A137626 A134179 A223145 * A164676 A004307 A268879

Adjacent sequences:  A188222 A188223 A188224 * A188226 A188227 A188228

KEYWORD

nonn

AUTHOR

Zoltán Lőrincz, Mar 30 2011

STATUS

approved

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Last modified December 3 08:07 EST 2021. Contains 349445 sequences. (Running on oeis4.)