A226277 - OEIS

%I #3 Jul 09 2013 15:00:37

%S 1,25,3125,4096,15625,19683,46656,59049,78125,117649,279936,1953125,

%T 4782969,5764801,10077696,387420489

%N Numbers m of the form u^v where u and v are digits in decimal representation of m.

%C a(n) occurs in a(n)-th row of table A226272.

%e a(1) = 1 = 1^1;

%e a(2) = 25 = 5^2;

%e a(3) = 3125 = 5^5;

%e a(4) = 4096 = 4^6;

%e a(5) = 15625 = 5^6;

%e a(6) = 19683 = 3^9;

%e a(7) = 46656 = 6^6;

%e a(8) = 59049 = 9^5;

%e a(9) = 78125 = 5^7;

%e a(10) = 117649 = 7^6;

%e a(11) = 279936 = 6^7;

%e a(12) = 1953125 = 5^9;

%e a(13) = 4782969 = 9^7;

%e a(14) = 5764801 = 7^8;

%e a(15) = 10077696 = 6^9;

%e a(16) = 387420489 = 9^9.

%e 256 = 2^8 = 4^4 is not a term, as neither 8 nor 4 occur in 256.

%o (Haskell)

%o import Data.List (sort)

%o a226277 n = a226277_list !! (n-1)

%o a226277_list = sort [w | u <- [0..9], v <- [0..9], let w = u ^ v,

%o    "0123456789" !! u `elem` show w, "0123456789" !! v `elem` show w]

%K nonn,base,fini,full

%O 1,2

%A _Reinhard Zumkeller_, Jul 09 2013