A176764 Smallest power of 4 whose decimal expansion contains n.

1024, 1, 256, 16384, 4, 256, 16, 1048576, 16384, 4096, 1024, 1099511627776, 1125899906842624, 1180591620717411303424, 262144, 288230376151711744, 16, 17179869184, 1073741824, 4194304, 72057594037927936, 262144, 4722366482869645213696

Offset

0,1

Comments

This is to 4 as A176763 is to 3 and as A030001 is to 2.

Links

Paolo Xausa, Table of n, a(n) for n = 0..10000

Formula

a(n) = MIN{A000302(i) such that n in decimal representation is a substring of A000302(i)}.

a(n) = 4^A062521(n). - Michel Marcus, Sep 30 2014

Example

a(1) = 1 because 4^0 = 1 has "1" as a substring (not a proper substring, though).
a(2) = 256 because 4^4 = 256 has "2" as a substring.
a(3) = 16384 because 4^7 = 16384 has "3" as a substring.

Mathematica

A176764[n_] := Block[{k = -1}, While[StringFreeQ[IntegerString[4^++k], IntegerString[n]]]; 4^k]; Array[A176764, 50, 0] (* Paolo Xausa, Apr 03 2024 *)

Crossrefs

Cf. A000302, A030001, A176763, A176765-A176773.

Sequence in context: A263168 A336779 A030001 * A351262 A336778 A084912

Adjacent sequences: A176761 A176762 A176763 * A176765 A176766 A176767

Keyword

base,easy,nonn

Author

Jonathan Vos Post, Apr 25 2010

Extensions

Corrected and extended by Sean A. Irvine and Jon E. Schoenfield, May 05 2010

a(0) prepended by Paolo Xausa, Apr 03 2024

Status

approved