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A054521
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Triangle T(n,k): T(n,k)=1 if GCD(n,k) = 1, T(n,k)=0 otherwise (n >= 1, 1<=k<=n).
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46
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1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Row sums = phi(n), A000010: (1, 1, 2, 2, 4, 2, 6,...). - Gary W. Adamson (qntmpkt(AT)yahoo.com), May 20 2007
Characteristic function of A169581: a(A169581(n))=1; a(A169582(n))=0. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 02 2009]
The function T(n,k) = T(k,n) is defined for k>n but only the values for 1<=k<=n as a triangular array are listed here.
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LINKS
| R. Zumkeller, Table of n, a(n) for n = 1..10000 [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 02 2009]
Index entries for characteristic functions [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 02 2009]
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FORMULA
| a(n) = A000007(A050873(n)). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 02 2009]
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EXAMPLE
| {1}, {1,0}, {1,1,0}, {1,0,1,0}, {1,1,1,1,0}, {1,0,0,0,1,0}, ...
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MATHEMATICA
| T[ n_, k_] := Boole[ n>0 && k>0 && GCD[ n, k] == 1] (* Michael Somos Jul 17 2011 *)
T[ n_, k_] := If[ n<1 || k<1, 0, If[ k>n, T[ k, n], If[ k==1, 1, If[ n>k, T[ k, Mod[ n, k, 1]], 0]]] (* Michael Somos Jul 17 2011 *)
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PROG
| (PARI) {T(n, k) = n>0 && k>0 && gcd(n, k)==1} /* Michael Somos Jul 17 2011 */
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CROSSREFS
| Cf. A051731, A054522, ...
Cf. A054521.
Sequence in context: A136442 A168030 A128431 * A014240 A014471 A071028
Adjacent sequences: A054518 A054519 A054520 * A054522 A054523 A054524
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KEYWORD
| nonn,tabl
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Apr 09 2000
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