A063426 Smallest k such that 2^k has exactly n 2's in its decimal representation.

2, 1, 18, 43, 41, 93, 81, 107, 125, 177, 174, 196, 200, 197, 280, 265, 320, 348, 330, 481, 492, 486, 314, 449, 535, 509, 505, 616, 686, 742, 577, 598, 743, 788, 991, 885, 941, 810, 987, 934, 963, 970, 1165, 1018, 984, 1125, 928, 1279, 1126, 1232, 1164

Offset

0,1

Links

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

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[2^k], 2] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a

Prog

(PARI) a(n)={my(k=1); while(n<>#select(d->d==2, digits(2^k)), k++); k} \\ Harry J. Smith, Aug 23 2009, Andrew Howroyd, Jun 26 2018

Crossrefs

Cf. A063115, A063429, A063430, A063526, A063540, A063552, A063553, A063554.

Sequence in context: A089512 A300956 A089014 * A316195 A266010 A349960

Adjacent sequences: A063423 A063424 A063425 * A063427 A063428 A063429

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 25 2018

Status

approved