A023415 If any power of 2 ends with k 8's and 9's, they must be the first k terms of this sequence in reverse order.

8, 8, 8, 9, 8, 9, 9, 8, 9, 8, 9, 8, 8, 9, 9, 8, 9, 8, 9, 9, 9, 8, 8, 8, 8, 9, 8, 8, 8, 8, 9, 9, 9, 9, 8, 9, 8, 8, 9, 9, 8, 8, 9, 9, 8, 9, 8, 8, 9, 8, 9, 8, 9, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 8, 9, 8, 8, 8, 9, 9, 8, 8, 9, 8, 8, 9, 9, 8, 8, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 8, 8, 9, 8, 8, 9, 9, 9, 9, 9, 9, 8, 8, 8, 9, 9, 8, 8, 8

Offset

1,1

Comments

Upper limit of backward value of 2^n and n!. - Simon Plouffe, Mar 23 2009

Links

Ray Chandler, Table of n, a(n) for n = 1..10000

Prog

(Python)
# upper limit of backward value of 2^n
a, i=8, 0; x=a
while i < 200:
     i+=1; print(x, end=', ')
     if a%2**(i+1) == 0: x=8
     else: x=9
     a+=x*10**i
# Cezary Glowacz, Mar 11 2017

Crossrefs

Cf. A145679.

Sequence in context: A248762 A186985 A203127 * A294659 A134314 A242891

Adjacent sequences: A023412 A023413 A023414 * A023416 A023417 A023418

Keyword

nonn,base

Author

David W. Wilson

Status

approved