A068890 a(1) = 1; a(n) = smallest nontrivial n-th power with property that digits alternate in parity.

1, 4, 8, 16, 32, 729, 2187, 256

Offset: 1

Author

Amarnath Murthy, Mar 20 2002

Keywords

• nonn
• base
• fini

Comments

Conjecture: the sequence is finite.

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

Crossrefs

Cf. A030152, A068891.