OFFSET
1,1
COMMENTS
All terms are equal to 2^n-2, except 5 and 90.
In base 2^n-2, we need 2 digits when there are n digits in binary.
In base 5, we need 3 digits for 5 digits in binary.
In base 90, we need 3 digits for 13 digits in binary.
EXAMPLE
In base 5 : 11111[2] = 111[5].
In base 90 : 1111111111111[2] = 111[90].
PROG
(Python) from math import *
.for b1 in range(2, 3):
....for b2 in range(b1+1, 10001):
........for m in range(2, 20):
............for n in range(2, m+1):
................if (1-b1**m)*(1-b2)==(1-b1)*(1-b2**n):
....................print "b1, b2=", b1, b2, " m, n=", m, n
CROSSREFS
KEYWORD
base,nonn,more
AUTHOR
Sébastien Dumortier and Bastien Lapeyre, Oct 11 2008
STATUS
approved