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A252664 Minimal nontrivial undulant (A046075) divisible by n, or 0 if no undulant is divisible by n.

%I A252664 #42 May 22 2025 10:21:41
%S A252664 101,202,141,212,505,252,161,232,171,1010,121,252,494,252,525,272,272,
%T A252664 252,171,2020,252,242,161,696,525,494,2727,252,232,3030,434,3232,363,
%U A252664 272,525,252,3737,494,585,4040,656,252,989,484,585,414,141,4848,343,5050
%N A252664 Minimal nontrivial undulant (A046075) divisible by n, or 0 if no undulant is divisible by n.
%C A252664 Undulants are numbers are of the form ababab..... with a and b distinct digits (base 10, a nonzero). An undulate is nontrivial if it has at least 3 digits. - _Danny Rorabaugh_, Apr 22 2015
%H A252664 Reiner Moewald, <a href="/A252664/b252664.txt">Table of n, a(n) for n = 1..499</a>
%e A252664 505 is the least entry of A046075 that is divisible by 5, so a(5) = 505. Since an undulant cannot end in 00, a(100)=0. - _Danny Rorabaugh_, Apr 22 2015
%o A252664 (Python)
%o A252664 feld = []
%o A252664 for n in range(3, 500):
%o A252664    for a in range(1, 10):
%o A252664       for b in range(10):
%o A252664          if a != b:
%o A252664             z_string = ""
%o A252664             for pos in range(n):
%o A252664                if pos % 2 == 0:
%o A252664                   z_string = z_string + str(a)
%o A252664                else:
%o A252664                   z_string = z_string + str(b)
%o A252664             z = int(z_string)
%o A252664             feld.append(z)
%o A252664 feld_length = len(feld)
%o A252664 for z in range (1, 150):
%o A252664    start = 0
%o A252664    while start < feld_length and feld[start] % z != 0:
%o A252664       start = start + 1
%o A252664    if start < feld_length:
%o A252664       print(z, feld[start])
%Y A252664 Cf. A046075.
%K A252664 nonn,base
%O A252664 1,1
%A A252664 _Reiner Moewald_, Mar 22 2015