A255743 a(1) = 1; for n > 1, a(n) = 9*8^{A000120(n-1)-1}.

1, 9, 9, 72, 9, 72, 72, 576, 9, 72, 72, 576, 72, 576, 576, 4608, 9, 72, 72, 576, 72, 576, 576, 4608, 72, 576, 576, 4608, 576, 4608, 4608, 36864, 9, 72, 72, 576, 72, 576, 576, 4608, 72, 576, 576, 4608, 576, 4608, 4608, 36864, 72, 576, 576, 4608, 576, 4608, 4608

Offset

1,2

Comments

Also, this is a row of the square array A255740.

Partial sums give A255764.

Links

Felix Fröhlich, Table of n, a(n) for n = 1..10000

Hsien-Kuei Hwang, Svante Janson, and Tsung-Hsi Tsai, Identities and periodic oscillations of divide-and-conquer recurrences splitting at half, arXiv:2210.10968 [cs.DS], 2022, p. 33.

Example

Written as an irregular triangle in which the row lengths are the terms of A011782, the sequence begins:
   1;
   9;
   9, 72;
   9, 72, 72, 576;
   9, 72, 72, 576, 72, 576, 576, 4608;
   ...

Mathematica

MapAt[Floor, Array[9*8^(DigitCount[# - 1, 2, 1] - 1) &, 55], 1] (* Michael De Vlieger, Nov 03 2022 *)

Prog

(PARI) a(n) = if (n==1, 1, 9*8^(hammingweight(n-1)-1)); \\ Michel Marcus, Mar 15 2015
(Python) # Python 3.10+
def A255743(n): return 1 if n == 1 else 9*(1<<((n-1).bit_count()-1)*3) # Chai Wah Wu, Nov 15 2022

Crossrefs

Cf. A000120, A151787, A147582, A151789, A151779, A151791, A151782, A255740, A255741, A255744, A255745, A255764.

Sequence in context: A241868 A243125 A270008 * A183893 A210052 A239225

Adjacent sequences: A255740 A255741 A255742 * A255744 A255745 A255746

Keyword

nonn

Author

Omar E. Pol, Mar 05 2015

Extensions

More terms from Michel Marcus, Mar 15 2015

Status

approved