|
|
A130544
|
|
Multiplicative persistence of n!!.
|
|
1
|
|
|
0, 0, 0, 0, 0, 1, 2, 1, 4, 2, 1, 1, 1, 3, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,7
|
|
COMMENTS
|
From 24!! on all the numbers have same digits equal to zero thus the persistence is equal to 1.
|
|
LINKS
|
|
|
EXAMPLE
|
6!!= 6*4*2= 48 --> 4*8=32 --> 3*2= 6 --> Persistence=2
13!!=135135 --> 1*3*5*1*3*5=225 -->2*2*5=20 --> 2*0=0 --> Persistence=3
|
|
MAPLE
|
P:=proc(n) local i, k, w, ok, cont; for i from 0 by 1 to n do k:=i; w:=i-2; while w>0 do k:=k*w; w:=w-2; od; w:=1; ok:=1; if k<10 then print(0); else cont:=1; while ok=1 do while k>0 do w:=w*(k-(trunc(k/10)*10)); k:=trunc(k/10); od; if w<10 then ok:=0; print(cont); else cont:=cont+1; k:=w; w:=1; fi; od; fi; od; end: P(100);
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|