A164654 a(n) = 2*a(n-2) for n > 2; a(1) = 3, a(2) = 8.

3, 8, 6, 16, 12, 32, 24, 64, 48, 128, 96, 256, 192, 512, 384, 1024, 768, 2048, 1536, 4096, 3072, 8192, 6144, 16384, 12288, 32768, 24576, 65536, 49152, 131072, 98304, 262144, 196608, 524288, 393216, 1048576, 786432, 2097152, 1572864, 4194304, 3145728

Offset

1,1

Comments

Interleaving of A007283 and A000079 without initial terms 1, 2, 4.

Binomial transform is A164303.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..100

Index entries for linear recurrences with constant coefficients, signature (0,2).

Formula

a(n) = (7+(-1)^n)*2^(1/4*(2*n-5+(-1)^n)).

G.f.: x*(3+8*x)/(1-2*x^2). - corrected by Klaus Brockhaus, Sep 18 2009

Mathematica

With[{lst2=2^Range[0, 20]}, Riffle[3*lst2, 8*lst2]] (* or *) LinearRecurrence[ {0, 2}, {3, 8}, 50](* Harvey P. Dale, Aug 20 2011 *)

Prog

(Magma) [ n le 2 select 5*n-2 else 2*Self(n-2): n in [1..41] ];
(Maxima) a[1]:3$ a[2]:8$ a[n]:=2*a[n-2]$ makelist(a[n], n, 1, 41); /* Bruno Berselli, May 23 2011
(PARI) a(n) = (7+(-1)^n)*2^((2*n-5+(-1)^n)/4) \\ Charles R Greathouse IV, Jun 11 2015

Crossrefs

Cf. A007283 (3*2^n), A000079 (powers of 2), A164303.

Sequence in context: A276574 A276584 A098737 * A225267 A320541 A366612

Adjacent sequences: A164651 A164652 A164653 * A164655 A164656 A164657

Keyword

nonn,easy

Author

Klaus Brockhaus, Aug 20 2009

Status

approved