OFFSET
1,1
LINKS
Indranil Ghosh, Table of n, a(n) for n = 1..25000 (terms 1..1000 from Harvey P. Dale)
Antti Karttunen and J. Moyer, C program for computing the initial terms of this sequence
EXAMPLE
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
MATHEMATICA
Select[Prime[Range[100]], DigitCount[#, 2, 1]<3+DigitCount[#, 2, 0]&] (* Harvey P. Dale, Aug 12 2016 *)
PROG
(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 <= (2+b0), return(1); , return(0); ); };
forprime(x = 2, 397, if(B(x), print1(x, ", "); ); );
\\ Washington Bomfim, Jan 12 2011
(Python)
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
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Antti Karttunen, Jun 04 2004
STATUS
approved