A147870 - OEIS

A147870

Number of steps required to erase a finite sequence of nonnegative integers in the following way: at the n-th step, if the last number of the string is 0, delete it; otherwise replace it with n copies of the next-smaller number.

%I #15 Apr 12 2020 02:26:59

%S 1,2,4,14,22539988369406

%N Number of steps required to erase a finite sequence of nonnegative integers in the following way: at the n-th step, if the last number of the string is 0, delete it; otherwise replace it with n copies of the next-smaller number.

%C The fifth term is much larger than Skewes's number.

%C The starting string for a(n) is the length 1 string containing n.

%H Sudoku.com, off-topic, <a href="http://forum.enjoysudoku.com/how-not-to-erase-pencil-marks-t3995.html">How NOT to erase pencil-marks!</a> [From Martin Chan (martin.chan(AT)westminster.org.uk), Jun 06 2010]

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Skewes's_number">Skewes's number</a>.

%e 3 is erased in 14 steps:

%e 3->2->11->1000->100->10->1->0000000->000000->00000->0000->000->00->0->x

%K nonn

%O 0,2

%A Martin Chan (martin.chan(AT)westminster.org.uk), Nov 16 2008