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A343403 Numbers k such that the product of the digits of k is not the product of digits of any earlier term in the sequence. 2
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 25, 26, 27, 28, 29, 35, 37, 38, 39, 45, 47, 48, 49, 55, 56, 57, 58, 59, 67, 68, 69, 77, 78, 79, 88, 89, 99, 255, 256, 257, 258, 259, 267, 268, 269, 277, 278, 279, 288, 289, 299, 355, 357, 358, 359, 377, 378, 379, 388, 389, 399, 455 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Observations:
The digits 0 and 1 appear only in terms 0 and 1, respectively.
Terms cannot contain two 2s, two 3s, a 2 and a 3, a 2 and a 4, a 3 and a 4, or a 4 and a 6.
Digits in each term appear in ascending order (A009994).
LINKS
MAPLE
# product of digits
A007954 := proc(n::integer)
if n = 0 then
0;
else
mul( d, d=convert(n, base, 10)) ;
end if;
end proc:
hit:=Array(0..10000, -1);
a:=[0];
hit[0]:=0;
for n from 1 to 50000 do p:=A007954(n);
if p>0 and hit[p]=-1 then hit[p]:=n; a:=[op(a), n]; fi; od:
a; # N. J. A. Sloane, Apr 14 2021
PROG
(Python 3.7)
def getBaseTen(howMany=100):
listToReturn = []
listOfObtainedValues = []
count = 0
while len(listToReturn) < howMany:
afterOnePermutation = 1
for num in str(count):
afterOnePermutation *= int(num)
if afterOnePermutation is 0:
break
if not afterOnePermutation in listOfObtainedValues:
listToReturn.append(str(count))
listOfObtainedValues.append(afterOnePermutation)
count += 1
return listToReturn
(PARI) See Links section.
CROSSREFS
Cf. A003001, A007954, A009994 (ascending digits), A031346, A068189, A343160.
Sequence in context: A069716 A095289 A174141 * A095706 A280249 A096867
KEYWORD
nonn,base
AUTHOR
Collin King, Apr 14 2021
STATUS
approved

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Last modified July 18 21:02 EDT 2024. Contains 374388 sequences. (Running on oeis4.)