login
A280928
Composite numbers having the same digits as their prime factors (with multiplicity), including zero digits.
10
1255, 12955, 17482, 25105, 100255, 101299, 105295, 107329, 117067, 124483, 127417, 129595, 132565, 145273, 146137, 149782, 163797, 174082, 174298, 174793, 174982, 250105, 256315, 263155, 295105, 297463, 307183, 325615, 371893, 536539, 687919, 1002955, 1004251, 1012099, 1025095, 1029955
OFFSET
1,1
COMMENTS
Subsequence of A176670 as well as A020342.
Is this sequence the intersection of A176670 and A020342?
Excluding 1, all members of A080718 are members of this sequence. The first member of this sequence that is not a member of A080718 is a(17)=163797.
EXAMPLE
100255 is a member of this sequence as 100255 = 5*20051, which is exactly the same set of digits as 100255.
PROG
(SageMath)
def digits(x, n):
if((x<=0)|(n<2)):
return []
li=[]
while(x>0):
d=divmod(x, n)
li.append(d[1])
x=d[0]
li.sort()
return li;
def factorDigits(x, n):
if((x<=0)|(n<2)):
return []
li=[]
f=list(factor(x))
#ensures inequality of digits(x, n) and factorDigits(x, n) if x is prime
if((len(f)==1)&(f[0][1]==1)):
return [];
for c in range(len(f)):
for d in range(f[c][1]):
ld=digits(f[c][0], n)
li+=ld
li.sort()
return li;
#this variable affects the radix
radix=10
c=2
index=1
while(index<=100):
if(digits(c, radix)==factorDigits(c, radix)):
print(str(index)+" "+str(c))
index+=1
c+=1
print("complete")
CROSSREFS
The following sequences are all closely related: A020342, A014575, A080718, A280928, A048936, A144563.
Sequence in context: A062693 A067203 A230544 * A080718 A219993 A237562
KEYWORD
nonn,base
AUTHOR
Ely Golden, Jan 11 2017
STATUS
approved