cp's OEIS Frontend

A239437 Least number that is pandigital in some base >= n but not pandigital in bases 3 through n-1.

%I A239437 #21 May 22 2025 10:21:37
%S A239437 11,78,698,12280,179685,5518135,1037845296,1037845296,46935813565,
%T A239437 2860727439460,285947759601954,1018897102759406,672654273047783383
%N A239437 Least number that is pandigital in some base >= n but not pandigital in bases 3 through n-1.
%C A239437 Gives an upper bound on the testing needed to check membership in A239348.
%H A239437 Charles R Greathouse IV, <a href="/A239437/a239437.gp.txt">GP script for computing terms</a>
%F A239437 Trivially a(n) >= A049363(n) > n^(n-1).
%o A239437 (PARI) See Greathouse link.
%o A239437 (Python)
%o A239437 from itertools import permutations
%o A239437 from gmpy2 import digits
%o A239437 def A239437(n): # requires 3 <= n <= 62
%o A239437     m = n
%o A239437     while True:
%o A239437         s = ''.join([digits(i,m) for i in range(m)])
%o A239437         for d in permutations(s,m):
%o A239437             if d[0] != '0':
%o A239437                 c = mpz(''.join(d),m)
%o A239437                 for b in range(3,n):
%o A239437                     if len(set(digits(c,b))) == b:
%o A239437                         break
%o A239437                 else:
%o A239437                     return int(c)
%o A239437         m += 1 # _Chai Wah Wu_, May 31 2015
%Y A239437 Subsequence of A154314. Cf. A239348.
%K A239437 nonn,base,hard
%O A239437 3,1
%A A239437 _Charles R Greathouse IV_, Mar 18 2014
%E A239437 a(15) from _Giovanni Resta_, Mar 19 2014