

A126206


Number of 4's in decimal expansion of 4^n.


6



0, 1, 0, 1, 0, 1, 1, 1, 0, 2, 1, 3, 0, 1, 2, 2, 2, 1, 1, 3, 0, 3, 3, 3, 2, 2, 2, 3, 1, 2, 2, 3, 4, 3, 1, 3, 3, 4, 2, 4, 2, 4, 2, 2, 3, 4, 3, 3, 3, 3, 2, 2, 3, 5, 2, 4, 2, 4, 4, 3, 3, 3, 4, 4, 6, 5, 5, 4, 2, 9, 5, 2, 4, 6, 4, 7, 4, 2, 5, 4, 3, 4, 8, 4, 7, 9, 2, 8, 4, 7, 3, 10, 9, 5, 3, 5, 8, 8, 3, 10, 4
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OFFSET

0,10


LINKS

Table of n, a(n) for n=0..100.


EXAMPLE

a(11)=3 because 4^11=4194304 with three 4's.


MAPLE

P:=proc(n) local i, k, x, y, w, cont; y:=4; k:=y; for i from 0 by 1 to n do x:=y^i; cont:=0; while x>0 do w:=xtrunc(x/10)*10; if w=k then cont:=cont+1; fi; x:=trunc(x/10); od; print(cont); od; end: P(100);


MATHEMATICA

DigitCount[4^#, 10, 4]&/@Range[0, 150] [From Harvey P. Dale, Feb 01 2011]


CROSSREFS

Cf. A065710, A126205, A126207, A126208, A126209, A126210, A126211.
Sequence in context: A228786 A140699 A140256 * A119709 A253556 A252735
Adjacent sequences: A126203 A126204 A126205 * A126207 A126208 A126209


KEYWORD

nonn,base


AUTHOR

Paolo P. Lava and Giorgio Balzarotti, Dec 20 2006


STATUS

approved



