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.

A138837 Non-Mersenne primes: A000040 \ A000668.

Original entry on oeis.org

2, 5, 11, 13, 17, 19, 23, 29, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283
Offset: 1

Views

Author

Omar E. Pol, Apr 03 2008

Keywords

Comments

Primes that are not Mersenne primes A000668.
Pandigital primes in base 2. (Pandigital interpreted as including all digits, not necessarily only once each.) - Franklin T. Adams-Watters, May 11 2011
Primes whose sum of divisors is not a power of 2. - Omar E. Pol, Dec 19 2016

Links

Crossrefs

Primes in A133398.
Cf. A000040, A000203, A000668, A155151.

Programs

  • Mathematica
    max = 300; Complement[Prime[Range[PrimePi[max]]], 2^Range[Ceiling[Log[2, max]]] - 1] (* Alonso del Arte, Dec 30 2013 *)
  • PARI
    is_A138837(n)={isprime(n)&&1<M. F. Hasler, Feb 05 2014

Formula

A138837 = A000040 \ A000668. - M. F. Hasler, Feb 09 2014

Extensions

New name from Omar E. Pol, Jan 02 2014

A138836 Non-Mersenne numbers A001348.

Original entry on oeis.org

1, 2, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70
Offset: 1

Views

Author

Omar E. Pol, Apr 05 2008

Keywords

Comments

Numbers that are not in A001348.
a(1) to a(2042) equals A133398, then a(2043)=2048 <> A133398(2043)=2047.

Links

Crossrefs

Cf. A001348, A001690, A062289, A133398, A138837, A138888, A138890, A138891. A133398.

Programs

  • Python
    from sympy import primepi, prime
def A138836(n): return n+(k:=int(primepi((n).bit_length())-1))+int(n+k+1>=1<1 else 1 # Chai Wah Wu, Sep 10 2024

A138884 Numbers that are not even superperfect numbers.

Original entry on oeis.org

1, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65
Offset: 1

Views

Author

Omar E. Pol, Apr 06 2008

Keywords

Comments

Also, numbers that are not superperfect numbers A019279, if there are no odd superperfect numbers.

Crossrefs

Even superperfect numbers: A061652. Cf. A019279, A132999, A133398.
Showing 1-3 of 3 results.

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