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 A129760 Bitwise AND of binary representation of n-1 and n. 14
 0, 0, 2, 0, 4, 4, 6, 0, 8, 8, 10, 8, 12, 12, 14, 0, 16, 16, 18, 16, 20, 20, 22, 16, 24, 24, 26, 24, 28, 28, 30, 0, 32, 32, 34, 32, 36, 36, 38, 32, 40, 40, 42, 40, 44, 44, 46, 32, 48, 48, 50, 48, 52, 52, 54, 48, 56, 56, 58, 56, 60, 60, 62, 0, 64, 64, 66, 64, 68, 68, 70, 64, 72, 72, 74 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Also the number of Ducci sequences with period n. Also largest number less than n having in binary representation fewer ones than n has; A048881(n-1) = A000120(a(n)) = A000120(n)-1. - Reinhard Zumkeller, Jun 30 2010 LINKS R. Zumkeller, Table of n, a(n) for n = 1..10000 R. Brown and J. L. Merzel, The number of Ducci sequences with a given period, Fib. Quart., 45 (2007), 115-121. FORMULA a(n) = n AND n-1 Equals n - A006519(n). - N. J. A. Sloane, May 26 2008 From Johannes W. Meijer, Jun 22 2011: (Start) a((2*n-1)*2^p) = (2*n-2)*(2^p), p>=0. a(2*n-1) = (2*n-2), n>=1, and a(2^p+1) = 2^p, p>=1. (End) EXAMPLE a(6) = 6 AND 5 = binary 110 AND 101 = binary 100 = 4. MAPLE nmax := 75: for p from 0 to ceil(simplify(log(nmax))) do for n from 1 to ceil(nmax/(p+2)) do a((2*n-1)*2^p) := (2*n-2) * 2^p od: od: seq(a(n), n=1..nmax); # Johannes W. Meijer, Jun 22 2011, revised Jan 25 2013 MATHEMATICA Table[BitAnd[n, n - 1], {n, 1, 100}] (* Vladimir Joseph Stephan Orlovsky, Jul 19 2011 *) PROG (C) int a(int n) { return n & (n-1); } (PARI) a(n)=bitand(n, n-1) \\ Charles R Greathouse IV, Jun 23 2011 CROSSREFS Cf. A038712, A086799, A104594, A059991, A006519, A109168, A220466. Sequence in context: A228885 A323910 A166085 * A291330 A057377 A145811 Adjacent sequences:  A129757 A129758 A129759 * A129761 A129762 A129763 KEYWORD easy,nonn,hear,base AUTHOR Russ Cox, May 15 2007 STATUS approved

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Last modified May 26 13:05 EDT 2019. Contains 323586 sequences. (Running on oeis4.)