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 A137331 a(n) = 1 if the binary weight of n is prime, otherwise 0. 1
 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS FORMULA a(n) = A010051(A000120(n)). - R. J. Mathar, Apr 09 2008 EXAMPLE a(0) = 0 (binary). Bits set = 0, 0 not prime -> 0. a(1) = 1 (binary). Bits set = 1, 1 not prime -> 0. a(2) = 10 (binary). Bits set = 1, 1 not prime -> 0. a(3) = 11 (binary). Bits set = 2, 2 prime -> 1. MAPLE A000120 := proc(n) add(i, i=convert(n, base, 2)) ; end: A010051 := proc(n) if isprime(n) then 1 ; else 0 ; fi ; end: A137331 := proc(n) A010051(A000120(n)) ; end: seq(A137331(n), n=0..200) ; # R. J. Mathar, Apr 09 2008 MATHEMATICA Table[If[PrimeQ[Plus @@ IntegerDigits[n, 2]], 1, 0], {n, 0, 100}] (* Stefan Steinerberger, Apr 09 2008 *) PROG (PARI)f(n)={v=binary(n); s=0; for(k=1, #v, if(v[k]== 1, s++)); return(isprime(s))}; for(n=0, 104, if(f(n), print1("1, "), print1("0, "))) \\ Washington Bomfim, Jan 14 2011 CROSSREFS Begins the same as A135136, but differs starting at a(31). Sequence in context: A093385 A252743 A135136 * A093386 A219098 A288710 Adjacent sequences:  A137328 A137329 A137330 * A137332 A137333 A137334 KEYWORD nonn,easy,base AUTHOR George Pollard, Apr 07 2008 EXTENSIONS More terms from R. J. Mathar and Stefan Steinerberger, Apr 09 2008 STATUS approved

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Last modified December 5 12:24 EST 2021. Contains 349557 sequences. (Running on oeis4.)