OFFSET
1,2
COMMENTS
Supersequence of A213084.
There are (2 + 4^d)/3 terms with d digits, for each d >= 1. - Robert Israel, Mar 31 2017
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
1111 is in the sequence because 1*1*1*1 = 1 = 8^0.
MAPLE
dmax:= 4: # to get all terms with at most dmax digits
B[0, 1]:= {1, 8}:
B[1, 1]:= {2}:
B[2, 1]:= {4}:
for d from 2 to dmax do
for j from 0 to 2 do
B[j, d]:= map(t -> (10*t+1, 10*t+8), B[j, d-1])
union map(t -> 10*t+4, B[(j+1) mod 3, d-1])
union map(t->10*t+2, B[(j+2) mod 3, d-1])
od od:
seq(op(sort(convert(B[0, d], list))), d=1..dmax); # Robert Israel, Mar 31 2017
PROG
(Magma) Set(Sort([n: n in [1..10000], k in [0..20] | &*Intseq(n) eq 8^k]))
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Mar 26 2017
STATUS
approved