A118252 The least positive integer whose reversed binary representation does not occur in the concatenation of the reversed binary representations of all preceding terms.

1, 2, 3, 4, 8, 10, 11, 12, 15, 16, 22, 24, 27, 32, 35, 36, 38, 43, 44, 54, 59, 64, 66, 70, 76, 79, 83, 85, 88, 91, 95, 97, 99, 116, 122, 127, 128, 130, 132, 136, 140, 147, 148, 150, 155, 158, 163, 169, 170, 175, 176, 179, 182, 184, 192, 196, 201, 217, 232

Offset

1,2

Comments

See the variant A118250 for comments and examples.

Links

Michael De Vlieger, Table of n, a(n) for n = 1..10000

Mathematica

a = {1}; b = {1}; Do[k = b[[i - 1]] + 1; While[SequenceCount[Flatten@ a, Set[d, Reverse@ IntegerDigits[k, 2]]] != 0, k++]; a = Join[a, d]; AppendTo[b, k], {i, 2, 59}]; b (* Michael De Vlieger, Aug 21 2017 *)

Prog

(PARI) A118252(n, show=0, a=1)={my(c=[a], S=[], L); for(k=1, n, show & print1(a", "); while( setsearch(S, binary(a++)), ); c=concat(binary(a), c); S=[]; for(i=0, #c-L=#binary(a), c[i+1] & for(j=i+L, min(i+L+1, #c), S=setunion(S, Set(t=[vecextract(c, 2^j-2^i)]))))); a}  \\ M. F. Hasler, Dec 29 2012

Crossrefs

Cf. A118248 (variant without reversal), A118250 (the same with a(0)=0), A118251 (concatenation of terms in binary).

Cf. A190896.

Sequence in context: A292113 A082224 A030478 * A047456 A279000 A073465

Adjacent sequences: A118249 A118250 A118251 * A118253 A118254 A118255

Keyword

easy,nonn

Author

Leroy Quet, Apr 18 2006

Extensions

More terms from Graeme McRae, Apr 19 2006

Explicit definition from M. F. Hasler, Dec 29 2012

Status

approved