A155699 Last n-digit string to appear as the first n digits of a positive power of 2.

9, 97, 982, 7629, 95367, 997432, 9313225, 95367431

Offset

1,1

Comments

a(n) = floor(f(n) / 10^(floor(log_10(f(n))) - n + 1)) where f(n) = 2^A155700(n). (I.e., a(n) is the number composed of the first n digits of 2^A155700(n).)

Links

Table of n, a(n) for n=1..8.

Example

The powers of 2 having at least 2 digits are 16, 32, 64, 128, 256, ...; discarding all but their first 2 digits yields the sequence 16, 32, 64, 12, 25, ..., in which all 90 of the possible 2-digit numbers (10 through 99) eventually appear; the last to appear is 97 (at 2^279 = 9.713...*10^83), so a(2) = 97.

Crossrefs

Cf. A000079, A155700.

Sequence in context: A232229 A240780 A236672 * A230620 A155601 A241771

Adjacent sequences: A155696 A155697 A155698 * A155700 A155701 A155702

Keyword

nonn,base,more

Author

Jon E. Schoenfield, Jan 25 2009

Status

approved