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%I #9 Nov 24 2021 20:17:39
%S 1,4,8,16,32,729,2187,256
%N a(1) = 1; a(n) = smallest nontrivial n-th power with property that digits alternate in parity.
%C Conjecture: the sequence is finite.
%C For all n>=1, (n^10 mod 1000) is one of {0, 1, 24, 49, 176, 201, 224, 249, 376, 401, 424, 449, 576, 601, 624, 625, 649, 776, 801, 824, 849, 976}. None of these have digits of alternating parity, thus a(10) does not exist. - _Benjamin Chaffin_, Nov 24 2021
%Y Cf. A030152, A068891.
%K nonn,base,fini
%O 1,2
%A _Amarnath Murthy_, Mar 20 2002