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

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A027699 Evil primes: primes with even number of 1's in their binary expansion. 30
3, 5, 17, 23, 29, 43, 53, 71, 83, 89, 101, 113, 139, 149, 163, 197, 257, 263, 269, 277, 281, 293, 311, 317, 337, 347, 349, 353, 359, 373, 383, 389, 401, 449, 461, 467, 479, 503, 509, 523, 547, 571, 593, 599, 619, 643, 673, 683, 691, 739, 751, 773, 797, 811 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Comment from Vladimir Shevelev, Jun 01 2007: Conjecture: If pi_1(m) is the number of a(n) not exceeding m and pi_2(m) is the number of A027697(n) not exceeding m then pi_1(m) <= smaller than pi_2(m) for all natural m except m=5 and m=6. I verified this conjecture up to 10^9. Moreover I conjecture that pi_2(m)-pi_1(m) tends to infinity with records at the primes m=2, 13, 41, 61, 67, 79, 109, 131, 137, ...

REFERENCES

Fouvry, E.; Mauduit, C. Sommes des chiffres et nombres presque premiers. (French) [Sums of digits and almost primes] Math. Ann. 305 (1996), no. 3, 571--599. MR1397437 (97k:11029)

LINKS

T. D. Noe, Table of n, a(n) for n=1..10000

V. Shevelev, A conjecture on primes and a step towards justification

MATHEMATICA

Select[Prime[Range[200]], EvenQ[Count[IntegerDigits[ #, 2], 1]]&] - T. D. Noe, Jun 12 2007

PROG

(PARI) forprime(p=1, 999, norml2(binary(p))%2|print1(p", "))

(PARI) isA027699(p)=isprime(p)&!bittest(norml2(binary(p)), 0) \\ M. F. Hasler, Dec 12 2010

CROSSREFS

Cf. A027697, A066148, A066149.

Cf. A001969 (evil numbers), A129771 (evil odd numbers)

Cf. A130911 (prime race between evil primes and odious primes).

Sequence in context: A218624 A152078 A152079 * A153417 A069687 A079017

Adjacent sequences:  A027696 A027697 A027698 * A027700 A027701 A027702

KEYWORD

nonn,easy,base

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Erich Friedman.

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 7 07:15 EST 2016. Contains 278841 sequences.