A164683 a(n) = 8*a(n-2) for n > 2; a(1) = 1, a(2) = 8.

1, 8, 8, 64, 64, 512, 512, 4096, 4096, 32768, 32768, 262144, 262144, 2097152, 2097152, 16777216, 16777216, 134217728, 134217728, 1073741824, 1073741824, 8589934592, 8589934592, 68719476736, 68719476736, 549755813888

Offset: 1

Author

Klaus Brockhaus, Aug 22 2009

Keywords

• nonn
• easy

Comments

Interleaving of A001018 and A001018 without initial term 1.

Binomial transform is A083100. Second binomial transform is A164607.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..300
• Index entries for linear recurrences with constant coefficients, signature (0, 8).

Crossrefs

Cf. A001018 (powers of 8), A083100, A164607.

Programs

Magma

[ n le 2 select 7*n-6 else 8*Self(n-2): n in [1..26] ];

Mathematica

With[{c=8^Range[0,15]},Riffle[c,c]]//Rest (* Harvey P. Dale, Aug 08 2017 *)

Formula

a(n) = 2^(1/4*(6*n-3+3*(-1)^n)).

G.f.: x*(1+8*x)/(1-8*x^2).