OFFSET
2,1
COMMENTS
No digit=1 is permitted to avoid infinite number of solutions; a(n)=0 if A067734(n^n)=0.
LINKS
Chai Wah Wu, Table of n, a(n) for n = 2..100
FORMULA
a(n) is obtained as prime factors of n^n concatenated in order of magnitude and with repetitions; a(n)=0 if n has p > 7 prime factors.
EXAMPLE
n=10, 10^10=10000000000, a(5)=55555555552222222222.
PROG
(Python)
from sympy import factorint
def A068186(n):
if n == 1:
return 1
pf = factorint(n)
ps = sorted(pf.keys(), reverse=True)
if ps[0] > 7:
return 0
s = ''
for p in ps:
s += str(p)*(n*pf[p])
return int(s) # Chai Wah Wu, Aug 12 2017
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Labos Elemer, Feb 19 2002
EXTENSIONS
a(12) corrected by Chai Wah Wu, Aug 12 2017
STATUS
approved