cp's OEIS Frontend

A174904 Smallest number m such that A174903(m) = n.

%I A174904 #4 Sep 29 2014 02:27:39
%S A174904 1,6,18,12,105,24,36,48,495,60,400,192,144,120,4656,180,1600,240,576,
%T A174904 1120,10000,360,1296,2240,900,960,28920,720,25600,840,9216,5600,5184,
%U A174904 1260,102400,6160,36864,1680,302500,2880,19600,15360,3600,12320
%N A174904 Smallest number m such that A174903(m) = n.
%C A174904 A174903(a(n)) = n and A174903(m) <> n for m < a(n).
%e A174904 a(2)=18, A174903(18)=#{(2,3),(6,9)}=2;
%e A174904 a(3)=12, A174903(12)=#{(2,3),(3,4),(4,6)}=3;
%e A174904 a(4)=105, A174903(105)=#{(3,5),(5,7),(15,21),(21,35)}=4;
%e A174904 a(5)=24, A174903(24)=#{(2,3),(3,4),(4,6),(6,8),(8,12)}=5.
%o A174904 (Haskell)
%o A174904 import Data.List (elemIndex); import Data.Maybe (fromJust)
%o A174904 a174904 = (+ 1) . fromJust . (`elemIndex` map a174903 [1..])
%o A174904 -- _Reinhard Zumkeller_, Sep 29 2014
%K A174904 nonn
%O A174904 0,2
%A A174904 _Reinhard Zumkeller_, Apr 01 2010