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.

A095331 Number of A095321-primes in range ]2^n,2^(n+1)].

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 4, 15, 14, 52, 83, 199, 260, 850, 1204, 3435, 4596, 13102, 19095, 51386, 72485, 199933, 296317, 777795, 1152625, 3017298, 4571188, 11663138, 17768490, 45124684, 70038513
Offset: 1

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Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Ratios a(n)/A036378(n) converge as: 0, 0, 0, 0, 0, 0, 0, 0.023256, 0.053333, 0.109489, 0.054902, 0.112069, 0.095183, 0.123449, 0.085809, 0.148888, 0.11201, 0.168465, 0.118959, 0.17805, 0.136066, 0.191584, 0.141102, 0.202809, 0.15644, 0.213343, 0.164021, 0.222483, 0.174424, 0.230053, 0.180974, 0.23708, 0.18964

Crossrefs

a(n) = A036378(n)-A095330(n).

A095317 Primes in whose binary expansion the number of 1 bits is <= number of 0 bits minus 2.

Original entry on oeis.org

131, 137, 193, 257, 521, 523, 547, 577, 593, 641, 643, 673, 769, 773, 1031, 1033, 1049, 1061, 1091, 1093, 1097, 1153, 1217, 1283, 1289, 1297, 1409, 1553, 1601, 2053, 2063, 2069, 2081, 2083, 2087, 2089, 2099, 2113, 2129, 2131, 2137, 2153
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Crossrefs

Complement of A095316 in A000040. Subset: A095321. Subset of A095071. Cf. also A095327.

Programs

  • Mathematica
    Select[Prime[Range[400]],DigitCount[#,2,1]<=DigitCount[#,2,0]-2&] (* Harvey P. Dale, Dec 10 2017 *)
  • PARI
    forprime(p=2,2200,v=binary(p);s=0;for(k=1,#v,s+=if(v[k]==1,+1,-1));if(s<=-2,print1(p,", ")))
    \\ Washington Bomfim, Jan 13 2011

A095320 Primes in whose binary expansion the number of 1-bits is > number of 0-bits minus 3.

Original entry on oeis.org

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 263, 269
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Differs from primes (A000040) first time at n=55, where a(55)=263, while A000040(55)=257, as 257 whose binary expansion is 100000001, with 2 1-bits and 7 0-bits is the first prime excluded from this sequence. Note that 129 (10000001 in binary, 2 1-bits and 6 0-bits) is not prime.

Crossrefs

Complement of A095321 in A000040. Subset: A095316.
Cf. A095330.

Programs

  • Mathematica
    Select[Prime[Range[60]],DigitCount[#,2,1]>DigitCount[#,2,0]-3&] (* Harvey P. Dale, Jul 24 2013 *)
  • PARI
    forprime(p=2,269,v=binary(p);s=0;for(k=1,#v,    s+=if(v[k]==1,+1,-1));if(s>-3,print1(p,", "))) \\ Washington Bomfim, Jan 13 2011
Showing 1-3 of 3 results.