

A287515


a(n) = position of nth 0 when sequence is written in base 2.


1



2, 7, 8, 9, 11, 12, 15, 20, 21, 27, 29, 30, 32, 34, 38, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 62, 64, 65, 68, 70, 73, 74, 77, 78, 80, 83, 85, 86, 89, 91, 95, 98, 101, 108, 109, 110, 114, 116, 120, 127, 128, 134, 136, 137, 138, 139, 140, 141, 143, 144, 145, 146, 147, 150, 151, 152, 154, 155, 157, 158, 159, 162
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

A167500 lists the positions of 1s when the sequence is written in binary. This sequence lists the positions of 0s. When written in binary, it begins 10, 111, 1000, 1001, 1011... The first 0 appears at position 2, so a(1) = 2 = 10. The second 0 appears at position 7, so a(2) = 7 = 111. The third 0 appears at position 8, so a(3) = 8 = 1000. The sequence then becomes selfgenerating, because entries are added to it faster than 0s are detected in it.


LINKS

Anthony Sand, Table of n, a(n) for n = 1..10000


FORMULA

a(n) = zeropos([sequence],n)


EXAMPLE

a(1) = zeropos([10...],1) = 2
a(2) = zeropos([10,111,1000...],2) = 7
a(3) = zeropos([10,111,1000...],3) = 8
a(4) = zeropos([10,111,1000...],4) = 9
a(5) = zeropos([10,111,1000,1001...],5) = 11


PROG

(PARI) { zeroposseq()= smx=100; s=vector(smx); s[1]=2; s[2]=7; s[3]=8; si=0; dig=digits(s[1], 2); di=1; i=1; dl=0; while(si<smx, d=dig[i]; dl++; if(d==0, si++; s[si]=dl; print1(dl, ", "); ); i++; if(i>#dig, di++; dig=digits(s[di], 2); i=1; ); ); }


CROSSREFS

Cf. A167500, A167502.
Sequence in context: A064517 A270804 A167457 * A260581 A179772 A047354
Adjacent sequences: A287512 A287513 A287514 * A287516 A287517 A287518


KEYWORD

nonn,base,easy


AUTHOR

Anthony Sand, May 26 2017


STATUS

approved



