OFFSET
1,1
COMMENTS
All terms == 4*6^k (mod 6^(k+1)) for some k >= 1. However, not all numbers of this form are in the sequence, e.g., 888. - Robert Israel, Jun 13 2018
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
N:= 10^4: # for all terms <= N
filter:= proc(n) local L;
L:= convert(n-1, base, 6);
select(t -> L[t]=0 and L[t+1]=4, [$1..nops(L)-1])=[]
end proc:
S:= convert(`union`(seq({seq(i, i=4*6^k .. N, 6^(k+1))}, k=1..floor(log[6](N/4)))), list):
sort(select(filter, S)); # Robert Israel, Jun 13 2018
MATHEMATICA
SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 6], {4, 0}]>0, 1, 0], {n, 1500}], {0, 1}][[All, 2]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 17 2020 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
STATUS
approved