A176558 - OEIS
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
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)[]], `>`)[])):
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]))