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.

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

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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

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

Views

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).

A095333 Number of A095313-primes in range [2^n,2^(n+1)].

Original entry on oeis.org

1, 2, 2, 5, 7, 12, 23, 39, 72, 122, 246, 417, 799, 1376, 2779, 4846, 9569, 17092, 34351, 60653, 121738, 216916, 440337, 786408, 1601964, 2876617, 5895645, 10583728, 21674188, 39107151, 80559309, 145468029, 299785833
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Ratios a(n)/A036378(n) converge as: 1, 1, 1, 1, 1, 0.923077, 1, 0.906977, 0.96, 0.890511, 0.964706, 0.898707, 0.916284, 0.853598, 0.917162, 0.848835, 0.890222, 0.838254, 0.889116, 0.824246, 0.867475, 0.808736, 0.857174, 0.797721, 0.845756, 0.789034, 0.838964, 0.780401, 0.827029, 0.771382, 0.820504, 0.764271, 0.811717
Ratios a(n)/A095330(n) converge as: 1, 1, 1, 1, 1, 0.923077, 1, 0.928571, 1.014085, 1, 1.020747, 1.012136, 1.012674, 0.973815, 1.003249, 0.997325, 1.002514, 1.00808, 1.009166, 1.002794,1.004099, 1.000397, 0.997992, 1.000665, 1.002604, 1.003022, 1.003571,1.00371, 1.001761, 1.001864, 1.001805, 1.001771, 1.001674

Crossrefs

a(n) = A036378(n)-A095332(n).
Showing 1-3 of 3 results.