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A115927
a(n) is the number of k such that k and n*k, taken together, are pandigital.
11
0, 48, 6, 8, 12, 0, 1, 16, 3, 0, 0, 1, 1, 6, 3, 1, 19, 6, 4, 12, 0, 3, 3, 4, 3, 9, 2, 1, 8, 2, 0, 16, 1, 3, 14, 0, 3, 7, 3, 4, 0, 3, 1, 13, 4, 1, 6, 0, 1, 12, 0, 2, 28, 1, 4, 6, 1, 3, 6, 3, 0, 28, 1, 1, 10, 1, 1, 4, 5, 7, 0, 3, 3, 11, 0, 2, 8, 1, 1, 46, 0, 0, 5, 3, 1, 7, 5, 6, 8, 3, 0, 13, 2, 3
OFFSET
1,2
COMMENTS
There are 1549586 nonzero terms in a(n). The largest n for which a(n) > 0 is 987654320. The largest a(n) is a(2) = 48. - Chai Wah Wu, May 24 2015
EXAMPLE
a(7)=1 since there is only one number, k=14076, such that k and 7*k=98532.
a(9)=3 since there are 3 such numbers: 10638, 10647 and 10836.
PROG
(Python)
from itertools import permutations
l = {}
for d in permutations('0123456789', 10):
....if d[0] != '0':
........for i in range(9):
............if d[i+1] != '0':
................q, r = divmod(int(''.join(d[:i+1])), int(''.join(d[i+1:])))
................if not r:
....................if q in l:
........................l[q] += 1
....................else:
........................l[q] = 1
A115927_list = [0]*max(l)
for d in l:
....A115927_list[d-1] = l[d] # Chai Wah Wu, May 24 2015
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 06 2006
STATUS
approved