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 A163252 a(0) = 0, and a(n) is the least positive integer not occurring earlier in the sequence such that a(n-1) and a(n) differ in only one bit when written in binary. 12
 0, 1, 3, 2, 6, 4, 5, 7, 15, 11, 9, 8, 10, 14, 12, 13, 29, 21, 17, 16, 18, 19, 23, 22, 20, 28, 24, 25, 27, 26, 30, 31, 63, 47, 39, 35, 33, 32, 34, 38, 36, 37, 45, 41, 40, 42, 43, 59, 51, 49, 48, 50, 54, 52, 53, 55, 119, 87, 71, 67, 65, 64, 66, 70, 68, 69, 77, 73, 72, 74, 75, 79, 78 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Step from a(488) = 237 = 11101101_2 to a(489) = 749 = 1011101101_2 is the first case when one term is two binary digits longer than the previous. Considering the leading zeros, though, they still differ in only one bit. - Ivan Neretin, Jun 25 2015 LINKS Paul Tek, Table of n, a(n) for n = 0..10000 MAPLE N:= 10: # to get all terms before the first where a(n) >= 2^N B:= Array(0..2^N-1): B[0]:= 1: a[0]:= 0: L:= Vector([0\$N]): for n from 1 do   cands:= select(t -> B[t[1]]=0, [seq(`if`(L[i]=0, [a[n-1]+2^(i-1), i], [a[n-1]-2^(i-1), i]), i=1..N)]);   if nops(cands)=0 then break fi;   j:= min[index](map(t->t[1], cands));   a[n]:= cands[j][1];   i:= cands[j][2];   B[a[n]]:= 1;   L[i]:= 1 - L[i]; od: seq(a[i], i=0..n-1); # Robert Israel, Jun 25 2015 MATHEMATICA Nest[Append[#, Min[Complement[BitXor[#[[-1]], 2^Range[0, Floor[Log2[#[[-1]]]] + 2]], #]]] &, {0, 1}, 71] (* Ivan Neretin, Jun 25 2015 *) CROSSREFS Cf. A003188 Sequence in context: A265896 A254054 A303767 * A303773 A303769 A303775 Adjacent sequences:  A163249 A163250 A163251 * A163253 A163254 A163255 KEYWORD nonn,base AUTHOR Keenan Pepper, Jul 23 2009 STATUS approved

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Last modified August 3 10:49 EDT 2020. Contains 336198 sequences. (Running on oeis4.)