

A193414


Numbers m such that written in base 2 the structure of digits represents a valley.


2



1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 23, 25, 27, 29, 31, 33, 35, 39, 47, 49, 51, 55, 57, 59, 61, 63, 65, 67, 71, 79, 95, 97, 99, 103, 111, 113, 115, 119, 121, 123, 125, 127, 129, 131, 135, 143, 159, 191, 193, 195, 199, 207, 223, 225, 227, 231, 239, 241, 243
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OFFSET

1,2


COMMENTS

For n>1 the structure of digits of numbers written in base 2 represents a valley. The first digit is equal to the last digit (1). The first digits are in nonincreasing order. The last digits are in nondecreasing order. The numbers may have more 0 digits. Sequence is infinite.
See A193415  numbers m written in base 2: {1, 11, 101, 111, 1001, 1011, 1101, 1111, ...}.
Illustration using 67 = (1000011)_2:
1 . . . . 1 1
. 0 0 0 0 . .


LINKS

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


MATHEMATICA

Select[Range[300], MemberQ[{1, 3}, Length[Split[IntegerDigits[#, 2]]]] &] (* T. D. Noe, Jul 26 2011 *)


CROSSREFS

Cf. A193413 (Valley numbers written in base 10).
Sequence in context: A305468 A143452 A288452 * A138217 A074775 A225105
Adjacent sequences: A193411 A193412 A193413 * A193415 A193416 A193417


KEYWORD

nonn,base


AUTHOR

Jaroslav Krizek, Jul 25 2011


EXTENSIONS

First term corrected by Jaroslav Krizek, Jul 27 2011


STATUS

approved



