cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A095070 One-bit dominant primes, i.e., primes whose binary expansion contains more 1's than 0's.

Original entry on oeis.org

3, 5, 7, 11, 13, 19, 23, 29, 31, 43, 47, 53, 59, 61, 71, 79, 83, 89, 101, 103, 107, 109, 113, 127, 151, 157, 167, 173, 179, 181, 191, 199, 211, 223, 227, 229, 233, 239, 241, 251, 271, 283, 307, 311, 313, 317, 331, 347, 349, 359, 367, 373, 379, 383
Offset: 1

Views

Author

Antti Karttunen, Jun 01 2004

Keywords

Examples

			23 is in the sequence because 23 is a prime and 23_10 = 10111_2. '10111' has four 1's and one 0. - _Indranil Ghosh_, Jan 31 2017
		

Crossrefs

Intersection of A000040 and A072600.
Complement of A095075 in A000040.
Subsequence: A095073.
Cf. A095020.

Programs

  • Mathematica
    Select[Prime[Range[70]], Plus@@IntegerDigits[#, 2] > Length[IntegerDigits[#, 2]]/2 &] (* Alonso del Arte, Jan 11 2011 *)
    Select[Prime[Range[100]], Differences[DigitCount[#, 2]][[1]] < 0 &] (* Amiram Eldar, Jul 25 2023 *)
  • PARI
    B(x) = {nB = floor(log(x)/log(2)); b1 = 0; b0 = 0;
    for(i = 0, nB, if(bittest(x,i), b1++;, b0++;); );
    if(b1 > b0, return(1);, return(0););};
    forprime(x = 3, 383, if(B(x), print1(x, ", "); ); ); \\ Washington Bomfim, Jan 11 2011
    
  • PARI
    has(n)=hammingweight(n)>#binary(n)/2
    select(has, primes(500)) \\ Charles R Greathouse IV, May 02 2013
    
  • Python
    # Program to generate the b-file
    from sympy import isprime
    i=1
    j=1
    while j<=200:
        if isprime(i) and bin(i)[2:].count("1")>bin(i)[2:].count("0"):
            print(str(j)+" "+str(i))
            j+=1
        i+=1 # Indranil Ghosh, Jan 31 2017