A160417 a(n) = A160415(n+1)/4.

2, 1, 7, 1, 7, 3, 21, 1, 7, 3, 21, 3, 21, 9, 63, 1, 7, 3, 21, 3, 21, 9, 63, 3, 21, 9, 63, 9, 63, 27, 189, 1, 7, 3, 21, 3, 21, 9, 63, 3, 21, 9, 63, 9, 63, 27, 189, 3, 21, 9, 63, 9, 63, 27, 189, 9, 63, 27, 189, 27, 189, 81, 567, 1, 7, 3, 21, 3, 21, 9, 63, 3, 21

Offset

1,1

Links

Table of n, a(n) for n=1..73.

Mathematica

With[{d = 2}, wt[n_] := DigitCount[n, 2, 1]; f[n_] := If[OddQ[n], 3^d + (2^d) * Sum[(2^d - 1)^(wt[k] - 1), {k, 1, (n - 1)/2}] + (2^d)*(3^d - 2) * Sum[(2^d - 1)^(wt[k] - 1), {k, 1, (n - 3)/2}], 3^d + (2^d) * Sum[(2^d - 1)^(wt[k] - 1), {k, 1, n/2 - 1}] + (2^d)*(3^d - 2) * Sum[(2^d - 1)^(wt[k] - 1), {k, 1, n/2 - 1}]]; f[0] = 0; f[1] = 1; Differences[Array[f, 100]]/4] (* Amiram Eldar, Feb 02 2024 *)

Crossrefs

Cf. A152978, A160118, A160413, A160415.

Sequence in context: A305564 A354873 A345301 * A117044 A280691 A092666

Adjacent sequences: A160414 A160415 A160416 * A160418 A160419 A160420

Keyword

nonn

Author

Omar E. Pol, Jun 13 2009

Extensions

More terms from Max Alekseyev, Dec 12 2011

More terms from Amiram Eldar, Feb 02 2024

Status

approved