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.

A158671 Frequency of 0's in a constant bit representation of primes.

Original entry on oeis.org

1, 4, 10, 23, 47, 100, 202, 403, 798, 1592, 3171, 6293, 12578, 24987, 49796, 99190, 197699, 394227, 785804, 1567419, 3127966, 6242519, 12464093, 24887586, 49698098, 99261034, 198285886
Offset: 2

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Author

Jonathan Vos Post, Mar 24 2009

Keywords

Comments

From Table 1, p. 2, of Kak.

Examples

			The number of 0's and 1's for all primes with respect to different binary lengths from 2 to 27 is given in Table 1. Thus for all primes of binary length 3, we have the primes 2, 3, 5, and 7 which in the binary form are 010, 011, 101, and 111, with four 0's and 8 1's, so a(2) = 4. Likewise, for all primes of bit length 4, we count the primes 2, 3, 5, 7, 11, and 13 corresponding to the sequences 0010, 0011, 0101, 0111, 1011, 1101, which gives us ten 0's and 14 1's, so a(3) = 10.
		

Crossrefs

Programs

  • PARI
    an=0; c=0;
    f(n)={i=2^(n-1); j=2^n - 1; z=0; for(k=i,j, if(isprime(k), c++;v=binary(k);L=#v; for(m=1,L, if(v[m]==0,z++)))); return(z)};
    an=f(2); print1(an,", "); for(n=3,28,an=an+c+f(n);print1(an,", ")) \\ Washington Bomfim, Jan 19 2011

Extensions

a(28) from Washington Bomfim, Jan 19 2011