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a(n) = n + [n*r/t] + [n*s/t]; r=1, s=sin(Pi/8), t=cos(Pi/8).
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%I #11 Sep 08 2022 08:45:56

%S 2,4,7,9,12,14,16,19,21,24,26,28,32,34,37,39,42,44,46,49,51,54,56,58,

%T 62,64,67,69,72,74,76,79,81,84,86,88,92,94,97,99,101,104,106,109,111,

%U 114,116,118,122,124,127,129,131,134,136,139,141,144,146,148,152,154,157,159,161,164,166,169,171,173,176,178,182,184,187,189,191

%N a(n) = n + [n*r/t] + [n*s/t]; r=1, s=sin(Pi/8), t=cos(Pi/8).

%C See A189937.

%H G. C. Greubel, <a href="/A189939/b189939.txt">Table of n, a(n) for n = 1..10000</a>

%F A189937: a(n) = n + [n*sin(Pi/8)] + [n*cos(Pi/8)].

%F A189938: b(n) = n + [n*csc(Pi/8)] + [n*cot(Pi/8)].

%F A189939: c(n) = n + [n*sec(Pi/8)] + [n*tan(Pi/8)].

%t r=1; s=Sin[Pi/8]; t=Cos[Pi/8];

%t a[n_] := n + Floor[n*s/r] + Floor[n*t/r];

%t b[n_] := n + Floor[n*r/s] + Floor[n*t/s];

%t c[n_] := n + Floor[n*r/t] + Floor[n*s/t];

%t Table[a[n], {n, 1, 120}] (*A189937*)

%t Table[b[n], {n, 1, 120}] (*A189938*)

%t Table[c[n], {n, 1, 120}] (*A189939*)

%o (PARI) for(n=1,100, print1(n + floor(n/cos(Pi/8)) + floor(n*tan(Pi/8)), ", ")) \\ _G. C. Greubel_, Jan 13 2018

%o (Magma) C<i> := ComplexField(); [n + Floor(n/Cos(Pi(C)/8)) + Floor(n*Tan(Pi(C)/8)): n in [1..100]]; // _G. C. Greubel_, Jan 13 2018

%Y Cf. A189937, A189938.

%K nonn

%O 1,1

%A _Clark Kimberling_, May 01 2011