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A126206
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Number of 4's in decimal expansion of 4^n.
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6
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,10
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EXAMPLE
| a(11)=3 because 4^11=4194304 with three 4's.
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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:=x-trunc(x/10)*10; if w=k then cont:=cont+1; fi; x:=trunc(x/10); od; print(cont); od; end: P(100);
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MATHEMATICA
| DigitCount[4^#, 10, 4]&/@Range[0, 150] [From Harvey P. Dale, Feb 01 2011]
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CROSSREFS
| Cf. A065710, A126205, A126207, A126208, A126209, A126210, A126211.
Sequence in context: A182740 A140699 A140256 * A119709 A120251 A071490
Adjacent sequences: A126203 A126204 A126205 * A126207 A126208 A126209
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KEYWORD
| nonn,base
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AUTHOR
| Paolo P. Lava & Giorgio Balzarotti (paoloplava(AT)gmail.com), Dec 20 2006
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