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.
13 is in the sequence because 13 = 1101_2. '1101' has three 1's and one 0. 3 = 2 + 1. - _Indranil Ghosh_, Feb 07 2017
Select[Prime[Range[100]],DigitCount[#,2,1]<3+DigitCount[#,2,0]&] (* Harvey P. Dale, Aug 12 2016 *)
B(x) = { nB = floor(log(x)/log(2)); b1 = 0; b0 = 0;
for(i = 0, nB, if(bittest(x,i), b1++;, b0++;); );
if(b1 <= (2+b0), return(1);, return(0););};
forprime(x = 2, 397, if(B(x), print1(x, ", "); ); );
\\ Washington Bomfim, Jan 12 2011
from sympy import isprime
i=j=1
while j<=250:
if isprime(i) and bin(i)[2:].count("1")<=2+bin(i)[2:].count("0"):
print(str(j)+" "+str(i))
j+=1
i+=1 # Indranil Ghosh, Feb 07 2017
palindromicQ[n_, b_:10] := TrueQ[IntegerDigits[n, b] == Reverse[IntegerDigits[n, b]]]; Table[Length[Select[Range[2^(2n), 2^(2n + 1)], palindromicQ[#, 2] && PrimeQ[#] &]], {n, 10}] (* Alonso del Arte, Jan 13 2012 *)
m=vector(65536);u=vector(#m);u[1]=1;for(b=1,#m-1,c=b;e=2^floor(log(b+.5)/log(2));d=0;u[b+1]=e;while(c>0,d=d+e*(c%2);c=floor(c/2);e=e/2);m[b+1]=d);for(x=0,31,h=0;y=2^x;for(w=y,2*y-1,if(x<16,v1=4*y*w+m[w+1];v2=v1+2*y,w1=floor(w/65536);w2=w-65536*w1;v1=262144*y*w1+4*y*w2+65536*u[w1+1]/u[w2+1]*m[w2+1]+m[w1+1];v2=v1+2*y);if(isprime(v1),h++);if(isprime(v2),h++));print(2*x+3" bits: "h)) \\ Martin Raab, Jan 13 2012
Module[{nn = 21, s}, s = Select[8 Range[0, 2^nn] + 5, PrimeQ]; Table[Count[s, ?(2^n < # < 2^(n + 1) &)], {n, nn}]] (* _Michael De Vlieger, Jul 23 2017 *)
Module[{nn = 21, s}, s = Select[8 Range[0, 2^nn] + 7, PrimeQ]; Table[Count[s, ?(2^n < # < 2^(n + 1) &)], {n, nn}]] (* _Michael De Vlieger, Jul 23 2017 *)
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