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%I #13 Apr 03 2024 15:30:19
%S 1024,1,256,16384,4,256,16,1048576,16384,4096,1024,1099511627776,
%T 1125899906842624,1180591620717411303424,262144,288230376151711744,16,
%U 17179869184,1073741824,4194304,72057594037927936,262144,4722366482869645213696
%N Smallest power of 4 whose decimal expansion contains n.
%C This is to 4 as A176763 is to 3 and as A030001 is to 2.
%H Paolo Xausa, <a href="/A176764/b176764.txt">Table of n, a(n) for n = 0..10000</a>
%F a(n) = MIN{A000302(i) such that n in decimal representation is a substring of A000302(i)}.
%F a(n) = 4^A062521(n). - _Michel Marcus_, Sep 30 2014
%e a(1) = 1 because 4^0 = 1 has "1" as a substring (not a proper substring, though).
%e a(2) = 256 because 4^4 = 256 has "2" as a substring.
%e a(3) = 16384 because 4^7 = 16384 has "3" as a substring.
%t A176764[n_] := Block[{k = -1}, While[StringFreeQ[IntegerString[4^++k], IntegerString[n]]]; 4^k]; Array[A176764, 50, 0] (* _Paolo Xausa_, Apr 03 2024 *)
%Y Cf. A000302, A030001, A176763, A176765-A176773.
%K base,easy,nonn
%O 0,1
%A _Jonathan Vos Post_, Apr 25 2010
%E Corrected and extended by _Sean A. Irvine_ and _Jon E. Schoenfield_, May 05 2010
%E a(0) prepended by _Paolo Xausa_, Apr 03 2024