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A259346 If n = 2^k then a(n) = 3^k, otherwise a(n) = 0. 2

%I

%S 1,3,0,9,0,0,0,27,0,0,0,0,0,0,0,81,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,243,

%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,729,0,

%U 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0

%N If n = 2^k then a(n) = 3^k, otherwise a(n) = 0.

%H Amiram Eldar, <a href="/A259346/b259346.txt">Table of n, a(n) for n = 1..10000</a>

%H Lakhtakia, Akhlesh and Russell Messier, <a href="http://dx.doi.org/10.1016/0097-8493(89)90038-1">Self-similar sequences and chaos from Gauss sums</a>, Computers & Graphics, Vol. 13, No. 1 (1989), pp. 59-62. See Eq. (4a).

%H Lakhtakia, Akhlesh and Russell Messier, <a href="/A005821/a005821.pdf">Self-similar sequences and chaos from Gauss sums</a>, Computers & Graphics, Vol. 13, No. 1 (1989), pp. 59-62 (Annotated scanned copy).

%F Completely multiplicative with a(2) = 3, a(p) = 0 for odd prime p. - _Andrew Howroyd_, Jul 27 2018

%t a[n_] := With[{k = IntegerExponent[n, 2]}, If[n == 2^k, 3^k, 0]];

%t Array[a, 85] (* _Jean-Fran├žois Alcover_, Aug 27 2019 *)

%o (PARI) a(n)={my(e=valuation(n,2)); if(n == 2^e, 3^e, 0)} \\ _Andrew Howroyd_, Jul 27 2018

%K nonn,easy,mult

%O 1,2

%A _N. J. A. Sloane_, Jun 27 2015

%E More terms from _Jon E. Schoenfield_, Jun 28 2015

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Last modified May 15 17:11 EDT 2021. Contains 343920 sequences. (Running on oeis4.)