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A258055 Concatenation of the decimal representations of the lengths (increased by 1) of the runs of zeros between successive ones in the binary representation of n. 2
0, 0, 0, 1, 0, 2, 1, 11, 0, 3, 2, 21, 1, 12, 11, 111, 0, 4, 3, 31, 2, 22, 21, 211, 1, 13, 12, 121, 11, 112, 111, 1111, 0, 5, 4, 41, 3, 32, 31, 311, 2, 23, 22, 221, 21, 212, 211, 2111, 1, 14, 13, 131, 12, 122, 121, 1211, 11, 113, 112, 1121, 111, 1112, 1111 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

COMMENTS

Originally called the "Golden Book's ZI-sequence" by the author.

The ZI-sequence is related to the binary numbers sequence with 10 ^ n substituted by the respective exponent increased by 1 (i.e., 10 as 2, 100 as 3, etc.) and the least significant bit discarded, e.g., binary 1011 converts to ZI 21.

a(n) = 0 when no successive ones exist in the binary representation of n, i.e., when n=0 and when n is a power of 2. - Giovanni Resta, Aug 31 2015

LINKS

Table of n, a(n) for n=0..62.

A. Strazds, The Golden Book

EXAMPLE

Example for n=6: binary 110 => split into 10^m components: 1 (10^0) and 10 (10^1) => 1; the least significant bit, and thus the whole last component, here 10, is discarded.

840 in binary is 1100101000. The runs of zeros between successive ones have length 0, 2 and 1, hence a(840) = 132. - Giovanni Resta, Aug 31 2015

MATHEMATICA

a[0] = 0; a[n_] := FromDigits@ Flatten[ IntegerDigits /@ Most[ Length /@ (Split[ Flatten[ IntegerDigits[n, 2] /. 1 -> {1, 0}]][[2 ;; ;; 2]]) ]]; Table[a@ n, {n, 0, 100}] (* Giovanni Resta, Aug 31 2015 *)

PROG

(PHP)

function dec2zi ($d) {

$b = base_convert($d, 10, 2); $b = str_split($b);

$i = $z = 0; $r = "";

foreach($b as $v) {

if (!$v) {

$i++;

} else {

if ($i > 0) {

$r .= $i + $v; $i = 0;

} else {

if ($z > 0) {

$r .= $v; $z = 0;

}

$z++; }}}

return $r == "" ? 0 : $r; }

CROSSREFS

Cf. A248646, A256494. See also A261300 for another version.

Sequence in context: A271042 A098290 A160110 * A139393 A037916 A320390

Adjacent sequences:  A258052 A258053 A258054 * A258056 A258057 A258058

KEYWORD

nonn,base,easy

AUTHOR

Armands Strazds, May 17 2015

STATUS

approved

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Last modified December 5 13:26 EST 2019. Contains 329751 sequences. (Running on oeis4.)