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.

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A095283 Primes whose binary-expansion ends with an odd number of 1's.

Original entry on oeis.org

5, 7, 13, 17, 23, 29, 31, 37, 41, 53, 61, 71, 73, 89, 97, 101, 103, 109, 113, 127, 137, 149, 151, 157, 167, 173, 181, 193, 197, 199, 223, 229, 233, 241, 257, 263, 269, 277, 281, 293, 311, 313, 317, 337, 349, 353, 359, 373, 383, 389, 397, 401, 409
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Crossrefs

Intersection of A000040 & A079523. Complement of A095282 in A000040. Cf. A027697, A095293.

Programs

  • Maple
    q:= proc(n) local i, l, r; l, r:= convert(n, base, 2), 0;
          for i to nops(l) while l[i]=1 do r:=r+1 od; is(r, odd)
        end:
    select(q, [ithprime(i)$i=1..150])[];  # Alois P. Heinz, Dec 15 2019
  • Mathematica
    Select[Prime[Range[100]], MatchQ[IntegerDigits[#, 2], {b:(1)..}|{_, 0, b:(1)..} /; OddQ[Length[{b}]]]&] (* Jean-François Alcover, Jan 03 2022 *)
  • PARI
    is(n)=valuation(n+1,2)%2 && isprime(n) \\ Charles R Greathouse IV, Oct 09 2013
    
  • Python
    from sympy import isprime
    def ok(n): b = bin(n); return (len(b)-len(b.rstrip("1")))%2 and isprime(n)
    print([k for k in range(1, 401) if ok(k)]) # Michael S. Branicky, Jan 03 2022

A095284 Primes in whose binary expansion the number of 1 bits is > 5 + number of 0 bits.

Original entry on oeis.org

127, 191, 223, 239, 251, 383, 479, 503, 509, 751, 863, 887, 983, 991, 1013, 1019, 1021, 1279, 1471, 1531, 1663, 1759, 1783, 1787, 1789, 1951, 1979, 1999, 2011, 2027, 2029, 2039, 2543, 2551, 2557, 2687, 2879, 2927, 2939, 2999, 3023, 3037
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Crossrefs

Complement of A095285 in A000040. Subset of A095322. Subset: A095312. Cf. also A095286, A095294.

Programs

  • PARI
    B(x) = { nB = floor(log(x)/log(2)); b1 = 0; b0 = 0;
    for(i = 0, nB, if(bittest(x,i), b1++;, b0++;); );
    if(b1 > (5+b0), return(1);, return(0););};
    forprime(x = 31, 3037, if(B(x), print1(x, ", "); ); );
    \\ Washington Bomfim, Jan 12 2011

A095285 Primes in whose binary expansion the number of 1 bits is <= 5 + number of 0 bits.

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, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 193, 197, 199, 211, 227, 229, 233, 241, 257, 263, 269, 271, 277, 281, 283
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Differs from primes (A000040) first time at n=31, where a(31)=131, while A000040(31)=127, as 127 whose binary expansion is 1111111, with 7 1-bits and no 0-bits is the first prime excluded from this sequence. Note that 63 (111111 in binary) is not prime.

Crossrefs

Complement of A095284 in A000040. Subset: A095323. Subset of A095313, from which it differs first time at n=42, where a(42)=193 (11000001 in binary) while A095313(42)=191 (10111111 in binary). Cf. also A095286, A095295.

Programs

  • PARI
    B(x) = { nB = floor(log(x)/log(2)); b1 = 0; b0 = 0;
    for(i = 0, nB, if(bittest(x,i), b1++;, b0++;); );
    if(b1 <= (5+b0), return(1);, return(0););};
    forprime(x = 2, 283, if(B(x), print1(x, ", "); ); );
    \\ Washington Bomfim, Jan 12 2011

A095287 Primes in whose binary expansion the number of 1-bits is <= 1 + number of 0-bits.

Original entry on oeis.org

2, 5, 17, 19, 37, 41, 67, 71, 73, 83, 89, 97, 101, 113, 131, 137, 139, 149, 163, 193, 197, 257, 263, 269, 271, 277, 281, 283, 293, 307, 313, 331, 337, 353, 389, 397, 401, 409, 419, 421, 433, 449, 457, 521, 523, 541, 547, 557, 563, 569, 577, 587, 593, 601, 613
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Examples

			From _Indranil Ghosh_, Feb 03 2017: (Start)
5 is in the sequence because 5_10 = 101_2. '101' has two 1's and one 0.
17 is in the sequence because 17_10 = 10001_2. '10001' has two 1's and three 0's. (End)
		

Crossrefs

Complement of A095286 in A000040. Subset: A095075. Subset of A095315. Cf. also A095297.

Programs

  • Mathematica
    Select[Prime[Range[200]],DigitCount[#,2,1]<=1+DigitCount[#,2,0]&] (* Harvey P. Dale, Apr 18 2023 *)
  • PARI
    forprime(p=2,613,v=binary(p);s=0;for(k=1,#v,s+=if(v[k]==1,+1,-1));if(s<=1,print1(p,", "))) \\ Washington Bomfim, Jan 13 2011
    
  • Python
    from sympy import isprime
    i=1
    j=1
    while j<=250:
        if isprime(i) and bin(i)[2:].count("1")<=1+bin(i)[2:].count("0"):
            print(str(j)+" "+str(i))
            j+=1
        i+=1 # Indranil Ghosh, Feb 03 2017

A095312 Primes in whose binary expansion the number of 1-bits is > 6 + number of 0-bits.

Original entry on oeis.org

127, 383, 479, 503, 509, 991, 1019, 1021, 1279, 1471, 1531, 1663, 1759, 1783, 1787, 1789, 1951, 1979, 1999, 2011, 2027, 2029, 2039, 3067, 3581, 3583, 3823, 3967, 4027, 4079, 4091, 4093, 5087, 5119, 5503, 5623, 5879, 6007, 6011, 6047
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Crossrefs

Complement of A095313 in A000040. Subset of A095284. Cf. also A095332.

Programs

  • Mathematica
    n1bQ[n_]:=Module[{idn2=IntegerDigits[n,2]},Count[idn2,1]>6+Count[idn2,0]]; Select[Prime[Range[1000]],n1bQ] (* Harvey P. Dale, Jun 25 2014 *)
  • PARI
    forprime(p=2,6100,v=binary(p);s=0;for(k=1,#v,s+=if(v[k]==1,+1,-1));if(s>6,print1(p,", "))) \\ Washington Bomfim, Jan 13 2011

A095313 Primes in whose binary expansion the number of 1-bits is <= 6 + number of 0-bits.

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, 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
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Differs from primes (A000040) first time at n=31, where a(31)=131, while A000040(31)=127, as 127 whose binary expansion is 1111111, with 7 1-bits and no 0-bits is the first prime excluded from this sequence.

Crossrefs

Complement of A095312 in A000040. Subset: A095285, from which it differs first time at n=42, where a(42)=191 (10111111 in binary), while A095285(42)=193 (11000001 in binary). Cf. also A095333.

Programs

  • Mathematica
    Select[Prime[Range[100]],DigitCount[#,2,1]<= DigitCount[#,2,0]+6&] (* Harvey P. Dale, Aug 18 2016 *)
  • PARI
    forprime(p=2,269,v=binary(p);s=0;for(k=1,#v,s+=if(v[k]==1,+1,-1));if(s<=6,print1(p,", "))) \\ Washington Bomfim, Jan 13 2011

A095316 Primes in whose binary expansion the number of 1-bits is > number of 0-bits minus 2.

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, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 263, 269, 271, 277, 281
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Comments

Differs from primes (A000040) first time at n=32, where a(32)=139, while A000040(32)=131, as 131 whose binary expansion is 10000011, with 3 1-bits and 5 0-bits is the first prime excluded from this sequence.

Crossrefs

Complement of A095317 in A000040. Subset of A095320. Subset: A095074. Cf. also A095326.

Programs

  • Mathematica
    Select[Prime[Range[60]],DigitCount[#,2,1]>(DigitCount[#,2,0]-2)&] (* Harvey P. Dale, May 28 2012 *)
  • PARI
    forprime(p=2,281,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

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

A095318 Primes in whose binary expansion the number of 1 bits is > 3 + number of 0 bits.

Original entry on oeis.org

31, 47, 59, 61, 127, 191, 223, 239, 251, 367, 379, 383, 431, 439, 443, 463, 479, 487, 491, 499, 503, 509, 607, 631, 701, 719, 727, 733, 743, 751, 757, 761, 823, 827, 829, 859, 863, 877, 883, 887, 911, 919, 941, 947, 953, 967, 971, 983, 991
Offset: 1

Views

Author

Antti Karttunen, Jun 04 2004

Keywords

Crossrefs

Complement of A095319 in A000040. Subset of A095314. Subset: A095322. Cf. also A095328.

Programs

  • PARI
    B(x) = { nB = floor(log(x)/log(2)); b1 = 0; b0 = 0;
    for(i = 0, nB, if(bittest(x,i), b1++;, b0++;); );
    if(b1 > (3+b0), return(1);, return(0););};
    forprime(x = 2, 991, if(B(x), print1(x, ", "); ); );
    \\ Washington Bomfim, Jan 12 2011

A095319 Primes in whose binary expansion the number of 1 bits is <= 3 + number of 0 bits.

Original entry on oeis.org

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 37, 41, 43, 53, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 193, 197, 199, 211, 227, 229, 233, 241, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311
Offset: 1

Views

Author

Keywords

Comments

Differs from primes (A000040) first time at n=11, where a(11)=37, while A000040(11)=31, as 31 whose binary expansion is 11111, with 5 1-bits and no 0 bits is the first prime excluded from this sequence. - Jun 04 2004

Crossrefs

Complement of A095318 in A000040. Subset of A095323, subset: A095315. A095329.

Programs

  • Mathematica
    Select[Prime[Range[70]],DigitCount[#,2,1]Harvey P. Dale, Feb 22 2020 *)
  • PARI
    B(x) = { nB = floor(log(x)/log(2)); b1 = 0; b0 = 0;
    for(i = 0, nB, if(bittest(x,i), b1++;, b0++;); );
    if(b1 <= (3+b0), return(1);, return(0););};
    forprime(x = 2, 311, if(B(x), print1(x, ", "); ); );
    \\ Washington Bomfim, Jan 12 2011
Previous Showing 61-70 of 143 results. Next