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Number of bases in which both n and the reversal of n are 3-digit numbers.
3

%I #13 Oct 20 2024 04:08:39

%S 0,0,0,1,1,1,1,0,1,0,1,1,0,0,0,1,0,0,0,0,1,2,1,1,2,2,1,1,2,0,0,1,2,2,

%T 2,3,2,2,2,0,0,1,2,3,3,2,2,2,3,0,1,2,2,3,4,2,3,3,3,0,1,2,3,2,2,4,4,4,

%U 4,0,0,1,2,2,1,4,4,4,4,0,0,1

%N Number of bases in which both n and the reversal of n are 3-digit numbers.

%F a(n) = a(inv(n)).

%F a(A002113(n)) = A191291(A002113(n)).

%F a(n) <= min(A191291(n),A191291(inv(n))).

%e a(36)=3 since 36 is 3-digit number in bases 4,5,6 and 63 is 3-digit number in bases 4,5,6,7 such that we have 3 common bases.

%Y Cf. A002113, A191291.

%K nonn,base

%O 1,22

%A _Vladimir Shevelev_, May 30 2011