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.

Showing 1-3 of 3 results.

A177801 Record lengths of chains of consecutive evil primes, starting with A177748(n).

Original entry on oeis.org

2, 3, 5, 7, 8, 12, 16, 20, 23, 25, 26, 30, 31, 32, 34, 38, 39, 40, 41, 42, 44
Offset: 1

Views

Author

Vladimir Shevelev, Dec 12 2010

Keywords

Comments

In contrast to the sequence of all positive integers, where the length of every chain of consecutive evil numbers cannot exceed 2, we conjecture that for the sequence of primes such length is not bounded with growth of n.

Crossrefs

Cf. A177800 (odious version), A177748, A177798, A000069, A001969, A027697, A027699.

Programs

  • PARI
    {l=0;r=0; forprime( p=1, default(primelimit), if( bittest( norml2(binary(p)),0), l>r & print1(r=l ", "); l & l=0, l++))} \\ M. F. Hasler, Dec 12 2010

Extensions

Extended by D. S. McNeil, Dec 12 2010
a(18)-a(21) from Amiram Eldar, Dec 09 2020

A177798 First primes of record chains of consecutive primes such that all of them are odious (A027697).

Original entry on oeis.org

2, 7, 167, 199, 6271, 12227, 168713, 579907, 5937157, 6829751, 8059943, 66858173, 167857663, 661416709, 2322857987, 12012698381, 14641587607, 26304771553, 49671709081, 1244930533403, 1922085626009
Offset: 1

Views

Author

Vladimir Shevelev, Dec 12 2010

Keywords

Comments

The corresponding record lengths are: 1,3,6,9,11,15, etc. (A177800).

Crossrefs

Cf. A177748 (evil version), A000069, A001969, A027697, A027699, A177800.

Programs

  • PARI
    back(p,k)=while(k--,p=precprime(p-1));precprime(p-1)
r=s=0;forprime(p=2,1e9,if(hammingweight(p)%2,s++,if(s>r,r=s;print1(back(p,r)", "));s=0)) \\ Charles R Greathouse IV, Mar 29 2013

Extensions

More terms from D. S. McNeil, Dec 12 2010
a(20)-a(21) from Amiram Eldar, Dec 09 2020

A177800 The maximal length of the chain of consecutive primes starting with A177798(n) such that all of them are odious.

Original entry on oeis.org

1, 3, 6, 9, 11, 15, 17, 18, 22, 23, 25, 26, 28, 29, 33, 34, 35, 36, 38, 39, 42
Offset: 1

Views

Author

Vladimir Shevelev, Dec 12 2010

Keywords

Comments

In contrast to sequence of all positive integers, where the length of a chain of consecutive odious numbers cannot exceed 2, we conjecture that over primes the length is not bounded.

Crossrefs

Cf. A000069 (odious numbers), A177798, A177748, A001969, A027697, A027699.

Extensions

Extended by D. S. McNeil, Dec 12 2010
a(20)-a(21) from Amiram Eldar, Dec 09 2020
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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