A097415 Values of k such that the first digit of 2^k is 9.

53, 63, 73, 83, 93, 156, 166, 176, 186, 249, 259, 269, 279, 289, 352, 362, 372, 382, 445, 455, 465, 475, 485, 548, 558, 568, 578, 641, 651, 661, 671, 734, 744, 754, 764, 774, 837, 847, 857, 867, 930, 940, 950, 960, 970, 1033, 1043, 1053, 1063, 1126

Offset: 1

Author

Eric W. Weisstein, Aug 16 2004

Keywords

• nonn
• base

Comments

The asymptotic density of this sequence is 1 - log_10(9) = 0.045757... (A104140). - Amiram Eldar, Jan 27 2021

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Gelfand's Question.

Crossrefs

Cf. A000079, A104140.

Programs

Mathematica

Select[Range[1200],IntegerDigits[2^#][[1]]==9&] (* Harvey P. Dale, Nov 30 2019 *)