A063115 Smallest k such that 2^k has exactly n 1's in its decimal representation.

1, 4, 17, 34, 57, 77, 70, 114, 127, 122, 207, 195, 202, 168, 319, 345, 329, 283, 410, 431, 463, 313, 467, 541, 485, 507, 610, 634, 563, 669, 576, 826, 655, 720, 784, 907, 894, 887, 766, 927, 945, 1029, 933, 994, 1134, 1102, 1171, 1205, 1351, 1309, 1128

Offset

0,2

Links

Harry J. Smith, Table of n, a(n) for n = 0..150

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[2^k], 1] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
Join[{1}, With[{p2=Table[DigitCount[2^n, 10, 1], {n, 2000}]}, Table[ Position[ p2, m, 1, 1], {m, 50}]]//Flatten] (* Harvey P. Dale, Jun 10 2018 *)

Prog

(PARI) a(n)={my(k=1); while(n<>#select(d->d==1, digits(2^k)), k++); k} \\ Harry J. Smith, Aug 19 2009, Andrew Howroyd, Jun 26 2018

Crossrefs

Cf. A063426, A063429, A063430, A063526, A063540, A063552, A063553, A063554.

Sequence in context: A212756 A031040 A273675 * A009954 A031092 A120884

Adjacent sequences: A063112 A063113 A063114 * A063116 A063117 A063118

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 25 2018

Status

approved