login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A168162 Numbers n which do not exceed the sum of the binary digits in all primes <= n. 2
3, 5, 7, 8, 11, 13, 14, 19, 23, 31, 32, 47, 61 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence A168161 is a subsequence of the primes in this sequence.

LINKS

Table of n, a(n) for n=1..13.

FORMULA

A168162 = { n | n <= A095375(pi(n)) }, where pi(n) = A000720(n).

EXAMPLE

There is no prime <= 1 and 2 has only nonzero binary digit, therefore these numbers are not in the sequence.

However, a(1)=3 has two binary digits, so the total number of these equal 3.

Then, 4 is larger than this, but the prime p=5 again adds 2 nonzero binary digits adding to a total of 5=a(2).

Then 6 is larger than this, but the prime p=7 adds 3 more nonzero bits for a total of 8, such that a(3)=7 and a(4)=8 don't exceed this.

PROG

(PARI) s=0; for(n=1, 9999, isprime(n) && s+=norml2(binary(n)); n<=s & print1(n", "))

CROSSREFS

Sequence in context: A190333 A190061 A288624 * A047485 A024969 A296233

Adjacent sequences:  A168159 A168160 A168161 * A168163 A168164 A168165

KEYWORD

fini,full,nonn,base

AUTHOR

M. F. Hasler, Nov 22 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 22 20:51 EDT 2019. Contains 325226 sequences. (Running on oeis4.)