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%I #6 Apr 08 2013 11:21:43
%S 4,99,749,6249,31249,281249,781249,75781249,925781249,1425781249,
%T 86425781249,336425781249,4836425781249,69836425781249,19836425781249,
%U 7519836425781249,62519836425781249,12519836425781249,9512519836425781249,34512519836425781249
%N (2*5^(2^n) + (10^n)/2 - 1) mod 10^n: a sequence of trimorphic numbers ending (for n > 1) in 9.
%C a(n) is the unique positive integer less than 10^n such that a(n) + 2^(n-1) - 1 is divisible by 2^n and a(n) + 1 is divisible by 5^n.
%H Eric M. Schmidt, <a href="/A224475/b224475.txt">Table of n, a(n) for n = 1..1000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TrimorphicNumber.html">Trimorphic Number</a>
%H <a href="/index/Ar#automorphic">Index entries for sequences related to automorphic numbers</a>
%F a(n) = (A224473(n) + 10^n / 2) mod 10^n.
%o (Sage) def A224475(n) : return crt(2^(n-1)+1, -1, 2^n, 5^n)
%Y Cf. A033819. Converges to the 10-adic number A091661. The other trimorphic numbers ending in 9 are included in A002283, A198971, and A224473.
%K nonn,base
%O 1,1
%A _Eric M. Schmidt_, Apr 07 2013
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