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A189933 a(n) = n + [n*r/t] + [n*s/t]; r=1, s=(sin(pi/5))^2, t=(cos(pi/5))^2 4
2, 6, 8, 12, 14, 18, 20, 24, 26, 30, 32, 36, 38, 42, 44, 48, 50, 54, 58, 60, 64, 66, 70, 72, 76, 78, 82, 84, 88, 90, 94, 96, 100, 102, 106, 110, 112, 116, 118, 122, 124, 128, 130, 134, 136, 140, 142, 146, 148, 152, 154, 158, 160, 164, 168, 170, 174, 176, 180, 182, 186, 188, 192, 194, 198, 200, 204, 206, 210, 212, 216, 220, 222, 226, 228, 232, 234, 238, 240 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000

FORMULA

From G. C. Greubel, Jan 13 2018: (Start)

A005408:  a(n) = n + [n*(sin(pi/5))^2] + [n*(cos(pi/5))^2] = 2*n - 1.

A189932:  b(n) = n + [n*(csc(pi/5))^2] + [n*(cot(pi/5))^2].

A189933:  c(n) = n + [n*(sec(pi/5))^2] + [n*(tan(pi/5))^2]. (End)

MATHEMATICA

With[{s=Sin[Pi/5]^2, t=Cos[Pi/5]^2}, Table[n+Floor[n/t]+Floor[(n*s)/t], {n, 80}]] (* Harvey P. Dale, Feb 22 2013 *)

PROG

(PARI) for(n=1, 100, print1(n + floor(n/(cos(Pi/5))^2) + floor(n*(tan(Pi/5))^2), ", ")) \\ G. C. Greubel, Jan 13 2018

(MAGMA) C<i> := ComplexField(); [n + Floor(n/(Cos(Pi(C)/5))^2) + Floor(n*(Tan(Pi(C)/5))^2): n in [1..100]]; // G. C. Greubel, Jan 13 2018

CROSSREFS

Cf. A189932, A189935.

Sequence in context: A257056 A209249 A047238 * A229488 A307699 A226485

Adjacent sequences:  A189930 A189931 A189932 * A189934 A189935 A189936

KEYWORD

nonn

AUTHOR

Clark Kimberling, May 01 2011

STATUS

approved

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Last modified April 6 20:39 EDT 2020. Contains 333286 sequences. (Running on oeis4.)