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Smallest number with n as multiplicative projection.
3

%I #15 Mar 30 2012 18:51:10

%S 1,2,3,4,5,6,7,16,27,10,11,12,13,14,15,256,17,24,19,20,21,22,23,36,

%T 3125,26,19683,28,29,30,31,65536,33,34,35,72,37,38,39,80,41,42,43,44,

%U 135,46,47,144,823543,160,51,52,53,216,55,112,57,58,59,60,61,62

%N Smallest number with n as multiplicative projection.

%C A000026(a(n)) = n and A000026(m) <> n for m < a(n);

%C a(p^k) = p^(p^(k-1)), p prime, k > 0; the sequence is not multiplicative, but for coprime odd numbers u, v: a(u*v) = a(u) * a(v);

%C A078779 gives fixed points: a(A078779(n)) = A078779(n).

%o (Haskell)

%o import Data.List (elemIndex, findIndices)

%o import Data.Maybe (fromJust)

%o a193551 n = (fromJust $ elemIndex n a000026_list) + 1

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Aug 27 2011