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A176558
a(n) is the reverse concatenation of divisors of n.
34
1, 21, 31, 421, 51, 6321, 71, 8421, 931, 10521, 111, 1264321, 131, 14721, 15531, 168421, 171, 1896321, 191, 20105421, 21731, 221121, 231, 2412864321, 2551, 261321, 27931, 28147421, 291, 30151065321, 311, 32168421, 331131, 341721, 35751, 361812964321, 371
OFFSET
1,2
COMMENTS
Union of A089374(n) for n >= 1 and A175354(n) for n >= 2. - Jonathan Vos Post, Apr 17 2011
LINKS
EXAMPLE
For n=12; divisors of 12: 1,2,3,4,6,12; a(12)=1264321 (reverse concatenation).
MAPLE
a:= n-> parse(cat(sort([numtheory[divisors](n)[]], `>`)[])):
seq(a(n), n=0..40); # Alois P. Heinz, Dec 31 2020
MATHEMATICA
Table[FromDigits@ Flatten@ Map[IntegerDigits, Reverse@ Divisors@ n], {n, 34}] (* Michael De Vlieger, Jan 23 2017 *)
PROG
(PARI) a(n) = {s = ""; fordiv(n, d, s = concat(Str(d), s)); eval(s); } \\ Michel Marcus, Feb 16 2015
(Python)
from sympy import divisors
def a(n): return int("".join(str(d) for d in divisors(n)[::-1]))
print([a(n) for n in range(1, 35)]) # Michael S. Branicky, Dec 31 2020
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Apr 20 2010
EXTENSIONS
More terms from Charles R Greathouse IV, Apr 23 2010
Corrected by Jaroslav Krizek, Apr 26 2010
Edited by Charles R Greathouse IV, Apr 30 2010
STATUS
approved