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 1-7 of 7 results.

A095297 Number of A095287-primes in range ]2^n,2^(n+1)].

Original entry on oeis.org

0, 1, 0, 2, 2, 8, 7, 22, 27, 68, 80, 235, 343, 844, 1180, 2849, 4473, 10138, 15387, 37023, 58714, 134477, 213397, 494625, 802311, 1829183, 2965114, 6789809, 11185644, 25412867, 42048314, 95440507, 159433693
Offset: 1

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Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Ratios a(n)/A036378(n) converge as: 0, 0.5, 0, 0.4, 0.285714, 0.615385, 0.304348, 0.511628, 0.36, 0.49635, 0.313725, 0.506466, 0.393349, 0.523573, 0.389439, 0.499037, 0.416132, 0.497205, 0.398266, 0.503126, 0.418382, 0.501376, 0.415405, 0.501741, 0.42358, 0.501731, 0.421943, 0.500653, 0.426814, 0.501264, 0.428266, 0.501433, 0.431691
Ratios a(n)/A095334(n) converge as: 1, 1, 1, 0.666667, 0.666667, 1.6, 1.75, 1.047619, 0.84375, 0.985507, 0.833333, 1.026201,1.023881, 1.098958, 1.057348, 0.996154, 1.023336, 0.98888, 0.993351,1.012581, 1.011595, 1.005518, 1.016781, 1.006987, 1.008436, 1.006948,1.004514, 1.002615, 1.003668, 1.00507, 1.006392, 1.005748, 1.004982

Crossrefs

a(n) = A036378(n)-A095296(n). Cf. A095298.

A095334 Number of A095314-primes in range ]2^n,2^(n+1)].

Original entry on oeis.org

0, 1, 0, 3, 3, 5, 4, 21, 32, 69, 96, 229, 335, 768, 1116, 2860, 4371, 10252, 15490, 36563, 58041, 133739, 209875, 491193, 795599, 1816561, 2951789, 6772098, 11144763, 25284670, 41781268, 94895078, 158643268
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Ratios a(n)/A036378(n) converge as: 0, 0.5, 0, 0.6, 0.428571, 0.384615, 0.173913, 0.488372, 0.426667, 0.50365, 0.376471, 0.493534, 0.384174, 0.476427, 0.368317, 0.500963, 0.406642, 0.502795, 0.400932, 0.496874, 0.413586, 0.498624, 0.408549, 0.498259, 0.420036, 0.498269, 0.420047, 0.499347, 0.425255, 0.498736, 0.425546, 0.498567, 0.429551
Ratios a(n)/A095297(n) converge as: 1, 1, 1, 1.5, 1.5, 0.625, 0.571429, 0.954545, 1.185185, 1.014706, 1.2, 0.974468, 0.976676, 0.909953, 0.945763, 1.003861, 0.977197, 1.011245, 1.006694, 0.987575, 0.988538, 0.994512, 0.983496, 0.993061, 0.991634, 0.9931, 0.995506, 0.997392, 0.996345, 0.994955, 0.993649, 0.994285, 0.995042

Crossrefs

a(n) = A036378(n)-A095335(n). Cf. A095298.

A095742 Sum of A037888(p) for all primes p such that 2^n < p < 2^(n+1).

Original entry on oeis.org

0, 0, 2, 3, 9, 16, 35, 69, 148, 271, 628, 1167, 2629, 4830, 10597, 20083, 42928, 81579, 174223, 331314, 701382, 1340756, 2825575, 5422454, 11361615, 21873923, 45673361, 88161666, 183458213, 354899159, 736343490, 1427495050, 2954560104
Offset: 1

Views

Author

Antti Karttunen, Jun 12 2004

Keywords

Comments

Ratio a(n)/A036378(n) gives the average asymmetricity ratio for n-bit primes: 0, 0, 1, 0.6, 1.285714, 1.230769, 1.521739, 1.604651, 1.973333, 1.978102, 2.462745, 2.515086, 3.014908, 2.996278, 3.49736, 3.517779, 3.993674, 4.000932, 4.50946, 4.502405, 4.997877, 4.998792, 5.500352, 5.500462, 5.998361, 5.999852, 6.499427, 6.500684, 7.000277, 7.000323, 7.499731, 7.499885, 7.999929, etc. I.e. 2- and 3-bit odd primes are all palindromes, 4-bit primes need on average just a one-bit flip to become palindromes, etc.
Ratio (a(n)/A036378(n))/f(n), where f(n) is (n-1)/4 if n is odd and (n-2)/4 if n is even (i.e. it gives the expected asymmetricity for all odd numbers in range [2^n,2^(n+1)]) converges as follows: 1, 1, 2, 1.2, 1.285714, 1.230769, 1.014493, 1.069767, 0.986667, 0.989051, 0.985098, 1.006034, 1.004969, 0.998759, 0.999246, 1.00508, 0.998418, 1.000233, 1.002102, 1.000535, 0.999575, 0.999758, 1.000064, 1.000084, 0.999727, 0.999975, 0.999912, 1.000105, 1.00004, 1.000046, 0.999964, 0.999985, 0.999991, ...

Examples

			a(1)=0, as only prime in range ]2,4] is 3, which has palindromic binary expansion 11, i.e. A037888(3)=0. a(2)=0, as in range ]4,8] there are two primes 5 (101 in binary) and 7 (111 in binary) so A037888(5) + A037888(7) = 0. a(3)=2, as in range ]8,16] there are two primes, 11 (1011 in binary) and 13 (1101 in binary), thus A037888(11) + A037888(13) = 1+1 = 2.
		

Crossrefs

Cf. A095298, A095732 (sums of similar asymmetricity measures for Zeckendorf-expansion), A095753.

A095296 Number of A095286-primes in range ]2^n,2^(n+1)].

Original entry on oeis.org

1, 1, 2, 3, 5, 5, 16, 21, 48, 69, 175, 229, 529, 768, 1850, 2860, 6276, 10252, 23248, 36563, 81622, 133739, 300311, 491193, 1091809, 1816561, 4062176, 6772098, 15021634, 25284670, 56134342, 94895078, 209889612
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Ratios a(n)/A036378(n) converge as: 1, 0.5, 1, 0.6, 0.714286, 0.384615, 0.695652, 0.488372, 0.64, 0.50365, 0.686275, 0.493534, 0.606651, 0.476427, 0.610561, 0.500963, 0.583868, 0.502795, 0.601734, 0.496874, 0.581618, 0.498624, 0.584595, 0.498259, 0.57642, 0.498269, 0.578057, 0.499347, 0.573186, 0.498736, 0.571734, 0.498567, 0.568309
Ratios a(n)/A095335(n) converge as: 1, 1, 1, 1.5, 1.25, 0.625, 0.842105, 0.954545, 1.116279, 1.014706, 1.100629, 0.974468, 0.985102, 0.909953, 0.966562, 1.003861, 0.984008, 1.011245, 1.00445, 0.987575, 0.991822, 0.994512, 0.988408, 0.993061, 0.99389, 0.9931, 0.99673, 0.997392, 0.997286, 0.994955, 0.995265, 0.994285, 0.996248

Crossrefs

a(n) = A036378(n)-A095297(n). Cf. A095298.

A095353 Sum of 1-fibits in Zeckendorf-expansion A014417(p) summed for all primes p in range [Fib(n+1),Fib(n+2)[ (where Fib = A000045).

Original entry on oeis.org

0, 1, 1, 3, 2, 7, 7, 14, 23, 35, 56, 94, 155, 243, 402, 614, 1061, 1656, 2689, 4295, 6938, 11176, 18095, 29102, 46907, 75703, 122174, 197494, 317987, 514611, 829595, 1340861, 2166008, 3497040, 5645418, 9120129, 14733126, 23803219, 38460014
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Ratio a(n)/A095354(n) (i.e. average number of 1-fibits in Zeckendorf-expansions of primes p which Fib(n+1) <= p < Fib(n+2)) grows as: 1, 1, 1, 1.5, 2., 2.333333, 2.333333, 2.8, 3.285714, 3.181818, 3.5, 3.916667, 4.189189, 4.418182, 4.785714, 4.873016, 5.358586, 5.575758, 5.871179, 6.100852, 6.382705, 6.676225, 6.954266, 7.223132, 7.489542, 7.773978, 8.045173, 8.331323, 8.598659, 8.886546, 9.161734, 9.440489, 9.71936, 9.995484, 10.266207, 10.54327, 10.820602, 11.096084, 11.374267.
Ratio of that average compared to A010049(n)/A000045(n) (the expected value of that same sum computed for all integers in the same range) converges as: 1, 1, 0.666667, 0.9, 1, 1.037037, 0.919192, 0.99661, 1.063946, 0.945946, 0.96142, 1, 0.999059, 0.988519, 1.008389, 0.970278, 1.011305, 1.000122, 1.003368, 0.995592, 0.996635, 0.999338, 0.999601, 0.998575, 0.997298, 0.998427, 0.997837, 0.999078, 0.998056, 0.99941, 0.999296, 0.999567, 0.999834, 0.999811, 0.999265, 0.999347, 0.999451, 0.999382, 0.999555.

Examples

			a(1) = a(2) = 0, as there are no primes in ranges [1,2[ and [2,3[. a(3)=1 as in [3,5[ there is prime 3 with Fibonacci-representation 100. a(4)=3, as in [5,8[ there are primes 5 and 7, whose Fibonacci-representations are 1000 and 1010 respectively and we have three 1-fibits in total. a(5)=2, as in [8,13[ there is only one prime 11, with Zeckendorf-representation 10100.
		

Crossrefs

Cf. A095336, A095298 (similar sums and ratios computed in binary system).

Extensions

a(2) corrected by Chai Wah Wu, Jan 16 2020

A095765 Number of primes in range [2^n+1, 2^(n+1)] whose binary expansion begins '10' (A080165).

Original entry on oeis.org

0, 1, 1, 3, 4, 6, 12, 22, 38, 70, 130, 237, 441, 825, 1539, 2897, 5453, 10335, 19556, 37243, 70938, 135555, 259586, 497790, 956126, 1839597, 3544827, 6839282, 13212389, 25552386, 49472951, 95883938, 186011076, 361177503, 701906519
Offset: 1

Views

Author

Antti Karttunen, Jun 12 2004

Keywords

Comments

I.e., number of primes p such that 2^n < p < (2^n + 2^(n-1)).
Ratio a(n)/A036378(n) converges as follows: 0, 0.5, 0.5, 0.6, 0.571429, 0.461538, 0.521739, 0.511628, 0.506667, 0.510949, 0.509804, 0.510776, 0.505734, 0.511787, 0.507921, 0.507444, 0.507303, 0.506866, 0.506173, 0.506115, 0.505487, 0.505395, 0.505318, 0.504951, 0.504786, 0.504588, 0.504437, 0.504301, 0.50415, 0.504016, 0.503887, 0.503763, 0.503654
Ratio a(n)/A095766(n) converges as follows: 0, 1, 1, 1.5, 1.333333, 0.857143, 1.090909, 1.047619, 1.027027, 1.044776, 1.04, 1.044053, 1.023202, 1.048285, 1.032193, 1.030228, 1.029645, 1.027847, 1.025001, 1.024764, 1.022191, 1.021815, 1.021501, 1.020003, 1.019331, 1.01852, 1.017908, 1.017353, 1.016737, 1.016195, 1.015669, 1.015164, 1.014723
I think this explains also the bias present in ratios shown at A095297, A095298, etc.

Examples

			Table showing the derivation of the initial terms:
  n   2^n+1  2^(n+1)  a(n)   primes starting '10' in binary
  1     3       4      0       -
  2     5       8      1       5 = 101_2
  3     9      16      1      11 = 1011_2
  4    17      32      3      17 = 10001_2, 19 = 10011_2, 23 = 10111_2
		

Crossrefs

Programs

  • Mathematica
    a[n_] := PrimePi[2^n + 2^(n - 1) - 1] - PrimePi[2^n];
    Array[a, 35] (* Robert G. Wilson v, Jan 24 2006 *)

Formula

a(n) = A036378(n)-A095766(n).

Extensions

a(34) and a(35) from Robert G. Wilson v, Jan 24 2006
Edited, restoring meaning of name, by Peter Munn, Jun 27 2023

A095336 Sum of 1-fibits in Zeckendorf-expansion A014417(p) summed for all primes p in range ]2^n,2^(n+1)].

Original entry on oeis.org

1, 3, 3, 13, 20, 41, 76, 176, 325, 638, 1353, 2533, 5223, 10186, 20504, 40775, 80661, 163765, 318602, 649948, 1268922, 2571531, 5082895, 10217300, 20327307, 40399966, 82164918, 160343669, 324931245, 640501167, 1290990369, 2567150515
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Examples

			a(1)=1, as only prime in range ]2,4] is 3, whose Fibonacci-representation is 100. In the next range we have primes 5 and 7, whose Fibonacci-representations are 1000 and 1010 respectively, thus a(2)=3.
		

Crossrefs

Showing 1-7 of 7 results.