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A067042
Numbers in which the product of digits in even positions = product of digits in odd positions.
2
11, 22, 33, 44, 55, 66, 77, 88, 99, 100, 111, 122, 133, 144, 155, 166, 177, 188, 199, 200, 221, 242, 263, 284, 300, 331, 362, 393, 400, 441, 482, 500, 551, 600, 661, 700, 771, 800, 881, 900, 991, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007, 1008, 1009
OFFSET
1,1
LINKS
FORMULA
Asymptotics: For any n, let f(n) be the number of entries in this sequence that are less than n. Then f(n)/n approaches 1 as n goes to infinity. This is because among numbers with a large number of digits, almost all have 0's in both odd positions and even positions. - David Wasserman, Jan 16 2002
EXAMPLE
2364 is a member as 2*6 = 3*4.
PROG
(Python)
from math import prod
def ok(n):
s = str(n)
return s != '1' and prod(map(int, s[::2])) == prod(map(int, s[1::2]))
print([k for k in range(1010) if ok(k)]) # Michael S. Branicky, Nov 22 2021
CROSSREFS
Sequence in context: A160861 A302575 A302801 * A078273 A345391 A065571
KEYWORD
base,nonn,easy
AUTHOR
Amarnath Murthy, Dec 29 2001
EXTENSIONS
Corrected by David Wasserman, Jan 16 2002
More terms from Sascha Kurz, Mar 23 2002
STATUS
approved