A143095 (1, 2, 4, 8, ...) interleaved with (4, 8, 16, 32, ...).

1, 4, 2, 8, 4, 16, 8, 32, 16, 64, 32, 128, 64, 256, 128, 512, 256, 1024, 512, 2048, 1024, 4096, 2048, 8192, 4096, 16384, 8192, 32768, 16384, 65536, 32768, 131072, 65536, 262144, 131072, 524288, 262144, 1048576, 524288, 2097152, 1048576, 4194304

Offset

0,2

Comments

Partial sums are in A079360. a(n) = A076736(n+5). - Klaus Brockhaus, Jul 27 2009

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

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

Formula

Inverse binomial transform of A048655: (1, 5, 11, 27, 65, 157, ...).

a(n) = A135530(n+1). - R. J. Mathar, Aug 02 2008

From Klaus Brockhaus, Jul 27 2009: (Start)

a(n) = (5 - 3*(-1)^n) * 2^((2*n-1+(-1)^n)/4)/2.

a(n) = 2*a(n-2) for n > 1; a(0) = 1, a(1) = 4.

G.f.: (1+4*x)/(1-2*x^2). (End)

a(n+3) = a(n+2)*a(n+1)/a(n). - Reinhard Zumkeller, Mar 04 2011

Maple

seq(coeff(series((1+4*x)/(1-2*x^2), x, n+1), x, n), n = 0..45); # G. C. Greubel, Mar 13 2020

Mathematica

nn=30; With[{p=2^Range[0, nn]}, Riffle[Take[p, nn-2], Drop[p, 2]]] (* Harvey P. Dale, Oct 03 2011 *)

Prog

(PARI) for(n=0, 41, print1((5-3*(-1)^n)*2^(1/4*(2*n-1+(-1)^n))/2, ", ")) \\ Klaus Brockhaus, Jul 27 2009
(Maxima) A143095(n):=(5-3*(-1)^n)*2^(1/4*(2*n-1+(-1)^n))/2$
makelist(A143095(n), n, 0, 30); /* Martin Ettl, Nov 03 2012 */
(Sage) [(5 -3*(-1)^n)*2^((2*n-1+(-1)^n)/4)/2 for n in (0..45)] # G. C. Greubel, Mar 13 2020

Crossrefs

Cf. A048655.

Sequence in context: A080965 A083703 A066104 * A141073 A261830 A194038

Adjacent sequences: A143092 A143093 A143094 * A143096 A143097 A143098

Keyword

nonn,easy

Author

Gary W. Adamson & Roger L. Bagula, Jul 23 2008

Extensions

More terms from Klaus Brockhaus, Jul 27 2009

Status

approved