A096549 Least exponent k such that the lowest n digits in the decimal representation of 2^k are even.

1, 6, 10, 11, 19, 43, 50, 50, 71, 71, 523, 590, 590, 12106, 12106, 12106, 12106, 56590, 505206, 1570511, 1570511, 4033966, 4033966, 9525771, 24045606, 24045606, 57862019, 183002599, 183002599, 877875719, 877875719, 877875719, 3789535319

Offset

1,2

Comments

This problem was discussed in a thread "Power of 2 with all even digits?" in the newsgroup sci.math (Jun 25 2004) with contributions from Edwin Clark, James Waldby, Bertram Felgenhauer, Richard Tobin, Oskar Lanzi III and others.

Links

Table of n, a(n) for n=1..33.

Newsgroup sci.math, Power of 2 with all even digits?

Example

a(5)=19 because 2^19=524288 is the smallest power of 2 that has a decimal representation ending in 5 even digits.

Crossrefs

Cf. A000079, A068994.

Sequence in context: A039509 A277597 A068442 * A248757 A136812 A109397

Adjacent sequences: A096546 A096547 A096548 * A096550 A096551 A096552

Keyword

base,nonn

Author

Hugo Pfoertner, Jul 07 2004

Extensions

a(21) - a(35) from Richard Tobin (richard(AT)cogsci.ed.ac.uk), Jun 29 2004

Status

approved