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A089311
Write n in binary; a(n) = number of 0's in rightmost block of zeros, after dropping any trailing 0's.
2
0, 0, 0, 0, 0, 1, 0, 0, 0, 2, 1, 1, 0, 1, 0, 0, 0, 3, 2, 2, 1, 1, 1, 1, 0, 2, 1, 1, 0, 1, 0, 0, 0, 4, 3, 3, 2, 1, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 0, 3, 2, 2, 1, 1, 1, 1, 0, 2, 1, 1, 0, 1, 0, 0, 0, 5, 4, 4, 3, 1, 3, 3, 2, 2, 1, 1, 2, 1, 2, 2, 1, 3, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 0, 4, 3, 3
OFFSET
0,10
LINKS
EXAMPLE
9 = 1001 so a(9) = 2.
MATHEMATICA
bd[n_]:=Module[{s=Split[IntegerDigits[n, 2]]}, Which[Length[s]<3, 0, MemberQ[ Last[s], 1], Length[s[[-2]]], True, Length[s[[-3]]]]]; Array[bd, 120, 0] (* Harvey P. Dale, Dec 29 2013 *)
PROG
(PARI) a(n)=local(b, c, s):b=binary(n):c=length(b):while(!b[c], c=c-1):while(c>0&&b[c], c=c-1): if(c<=0, 0, s=0:while(!b[c], c=c-1:s=s+1):s) \\ Ralf Stephan
CROSSREFS
Cf. A089309-A089313. Different from A086784.
Sequence in context: A293133 A178471 A160381 * A086784 A104162 A145679
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Dec 22 2003
EXTENSIONS
More terms from Ralf Stephan, Feb 01 2004
STATUS
approved