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.

A095747 Maximally asymmetric odd primes in binary.

Original entry on oeis.org

3, 5, 7, 11, 13, 19, 23, 29, 43, 53, 71, 79, 83, 101, 109, 113, 151, 179, 233, 241, 271, 311, 331, 347, 397, 421, 457, 599, 683, 739, 797, 853, 937, 977, 1087, 1103, 1223, 1307, 1427, 1459, 1597, 1613, 1733, 2017, 2111, 2143, 2503, 2731, 3011
Offset: 1

Views

Author

Antti Karttunen, Jun 12 2004

Keywords

Comments

Primes p for which A037888(p) = floor((A070939(p)-2)/2). Those numbers contain just the first and last bits mirroring each other. Hence all the odd primes without leading zeros begin and end in 1 bits, the unique totally asymmetric prime being (10)_2 = 2.

Examples

			a(10)=(110101)2 since the symmetry is limited to the first and last bits. The number 47=(101111)2 is not a term because from left to right, the third bit matches with the fourth.
		

Crossrefs

Programs

  • PARI
    A070939(p)={return(floor(log(p)/log(2))+1)};
    A037888(p)={v=binary(p);s=0;j=#v;for(k=1,#v,s+=abs(v[k]-v[j]);j--);return(s/2);}; forprime(p=3,3011, if(A037888(p) ==floor((A070939(p)-2)/2),print1(p,", ")))

Extensions

Edited by Washington Bomfim, Jan 13 2011