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 1-2 of 2 results.

A144214 Primes with both a prime number of 0's and a prime number of 1's in their binary representations.

Original entry on oeis.org

17, 19, 37, 41, 79, 103, 107, 109, 131, 137, 151, 157, 167, 173, 179, 181, 193, 199, 211, 227, 229, 233, 241, 257, 367, 379, 431, 439, 443, 463, 487, 491, 499, 521, 541, 557, 563, 569, 577, 587, 601, 607, 613, 617, 631, 641, 647, 653, 659, 661, 677, 701, 709
Offset: 1

Views

Author

Leroy Quet, Sep 14 2008

Keywords

Examples

			79, a prime, in binary is 1001111. This has two 0's and has five 1's. Since both two and five are primes, 79 is included in the sequence.
		

Crossrefs

Programs

  • Maple
    A080791 := proc(n) local i,dgs ; dgs := convert(n,base,2) ; nops(dgs)-add(i,i=dgs) ; end: A000120 := proc(n) local i,dgs ; dgs := convert(n,base,2) ; add(i,i=dgs) ; end: isA144214 := proc(n) local no0,no1 ; no0 := A080791(n) ; no1 := A000120(n) ; isprime(n) and isprime(no0) and isprime(no1) ; end: for n from 1 to 1200 do if isA144214(n) then printf("%d,",n) ; fi; od: # R. J. Mathar, Sep 17 2008
  • Mathematica
    Select[Prime[Range[6! ]],PrimeQ[DigitCount[ #,2,0]]&&PrimeQ[DigitCount[ #,2,1]]&] (* Vladimir Joseph Stephan Orlovsky, Feb 16 2010 *)
  • Python
    from sympy import isprime
    def ok(n): return isprime(c:=n.bit_count()) and isprime(n.bit_length()-c) and isprime(n)
    print([k for k in range(710) if ok(k)]) # Michael S. Branicky, Dec 27 2023

Extensions

More terms from R. J. Mathar, Sep 17 2008

A169817 n-th prime with both a prime number of 0's and a prime number of 1's in binary representation minus n-th semiprime with both a prime number of 0's and a prime number of 1's in their binary representation.

Original entry on oeis.org

8, 9, 16, 19, 54, 77, 72, 71, 82, 72, 64, 66, 74, 79, 64, 63, 72, 77, 78, 93, 86, 88, 95, 102, 209, 218, 246, 245, 240, 258, 281, 278, 285, 304, 323, 238, 182, 187, 162, 142, 155, 136, 135, 124, 130, 139, 142, 138, 142, 134, 148, 166, 167, 174, 176, 168, 177, 174
Offset: 1

Views

Author

Juri-Stepan Gerasimov, May 25 2010

Keywords

Examples

			a(1)=A144214(1)-A178350(1)=17-9=8.
		

Crossrefs

Programs

  • Mathematica
    pn0Q[n_]:=PrimeQ[DigitCount[n,2,1]]&&PrimeQ[DigitCount[n,2,0]]; nn=600;Module[{ps=Select[Prime[Range[nn]],pn0Q],sps=Select[Range[nn], PrimeOmega[#]==2&&pn0Q[#]&],minlen},minlen=Min[Length[ps], Length[ sps]];First[#]-Last[#]&/@Thread[{Take[ps,minlen],Take[sps,minlen]}]] (* Harvey P. Dale, May 07 2012 *)

Formula

a(n)=A144214(n)-A178350(n).

Extensions

Corrected (96 replaced by 86, all numbers from a(27) on replaced) by R. J. Mathar, Jun 04 2010
Showing 1-2 of 2 results.