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A054533 Triangular array giving Ramanujan sum T(n,k) = c_n(k), for n >= 1, 1<=k<=n, where c_k(n) = Sum_{m=1..k, (m,k)=1} exp(2 Pi i m n / k). 13
1, -1, 1, -1, -1, 2, 0, -2, 0, 2, -1, -1, -1, -1, 4, 1, -1, -2, -1, 1, 2, -1, -1, -1, -1, -1, -1, 6, 0, 0, 0, -4, 0, 0, 0, 4, 0, 0, -3, 0, 0, -3, 0, 0, 6, 1, -1, 1, -1, -4, -1, 1, -1, 1, 4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 10, 0, 2, 0, -2, 0, -4, 0, -2, 0, 2, 0, 4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 12, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,6

REFERENCES

T. M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, page 160.

LINKS

T. D. Noe, Rows n=1..50 of triangle, flattened

EXAMPLE

1; -1,1; -1,-1,2; 0,-2,0,2; -1,-1,-1,-1,4; ...

MATHEMATICA

c[k_, n_] := Sum[ If[GCD[m, k] == 1, Exp[2 Pi*I*m*n/k], 0], {m, 1, k}]; A054533 = Flatten[ Table[c[n, k] // FullSimplify, {n, 1, 14}, {k, 1, n}] ] (* Jean-François Alcover, Jun 27 2012 *)

CROSSREFS

Cf. A054532, A054534, A054535.

Sequence in context: A026613 A117199 A052511 * A143232 A096030 A025815

Adjacent sequences:  A054530 A054531 A054532 * A054534 A054535 A054536

KEYWORD

sign,easy,nice,tabl

AUTHOR

N. J. A. Sloane, Apr 09 2000

STATUS

approved

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Last modified May 24 01:37 EDT 2013. Contains 225613 sequences.