A224512 Gray code variant of A147582.

1, 4, 12, 4, 12, 36, 12, 4, 12, 36, 108, 36, 12, 36, 12, 4, 12, 36, 108, 36, 108, 324, 108, 36, 12, 36, 108, 36, 12, 36, 12, 4, 12, 36, 108, 36, 108, 324, 108, 36, 108, 324, 972, 324, 108, 324, 108, 36, 12, 36, 108, 36, 108, 324, 108, 36, 12, 36, 108

Offset

1,2

Comments

A147582 is generated by using the binary weight of n, A000120 = wt().

Here instead, A224512 uses the Gray code weight, A005811 = gt().

Links

Table of n, a(n) for n=1..59.

Formula

a(1) = 1. For a(n)>1, a(n) = 4 * 3^(gt(n-1)-1).

Example

A003188(5-1) = 6 = 110 (base 2), so gt(5-1) = 2. Then a(5) = 12 = 4 * 3^1 = 12.

Prog

(PARI) gt(n) = sum(kk=1, n, (-1)^((kk/2^valuation(kk, 2)-1)/2)); \\ from A005811.
a(n) = if (n==1, 1, 4 * 3^(gt(n-1)-1)); \\ Michel Marcus, Apr 22 2013

Crossrefs

Cf. A147582, A224513.

Sequence in context: A307874 A230057 A205124 * A010296 A084351 A286682

Adjacent sequences: A224509 A224510 A224511 * A224513 A224514 A224515

Keyword

nonn

Author

Gary W. Adamson, Apr 08 2013

Status

approved