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A255604
Table read by antidiagonals, T(n,k) is integer part of the area of a regular k-gon with side length n.
3
0, 1, 1, 3, 4, 1, 6, 9, 6, 2, 10, 16, 15, 10, 3, 15, 25, 27, 23, 14, 4, 21, 36, 43, 41, 32, 19, 6, 27, 49, 61, 64, 58, 43, 24, 7, 35, 64, 84, 93, 90, 77, 55, 30, 9, 43, 81, 110, 127, 130, 120, 98, 69, 37, 11, 52, 100, 139, 166, 178, 173, 154, 123, 84, 44, 13, 62, 121, 172
OFFSET
1,4
COMMENTS
See illustration in the links.
FORMULA
T(n,k) = floor(k*n^2/(4*tan(Pi/k))), n >=1, k >=3.
EXAMPLE
See table in the links.
MATHEMATICA
t[n_, k_] := Floor[k*n^2/(4 Tan[Pi/k])]; Table[t[n - k + 1, k], {n, 3, 14}, {k, 3 , n}] // Flatten
(* to view table: Table[t[n, k], {k, 3, 6}, {n, 6}] // TableForm *) (* Robert G. Wilson v, Feb 28 2015 *)
PROG
(PARI){for(i=1, 20, for(n=3, i-1, a=floor(n*(i-n)^2/(4*tan(Pi/n))); print1(a, ", ")))}
CROSSREFS
Row 1: A011865.
Columns 1,2,3,4,10: A171971, A000290, A255605, A255606, A172526.
Sequence in context: A286577 A175323 A359268 * A132700 A193794 A281862
KEYWORD
nonn,tabl
AUTHOR
Kival Ngaokrajang, Feb 27 2015
STATUS
approved