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A256908
Initialization a(n)=0 for all n; if a(n)=0, a(n+kp)=n where p=prime(n) and k=0,1,2,...
1
1, 2, 1, 4, 1, 6, 1, 2, 1, 10, 1, 12, 1, 2, 1, 5, 1, 3, 1, 2, 1, 22, 1, 7, 1, 2, 1, 3, 1, 30, 1, 2, 1, 34, 1, 36, 1, 2, 1, 40, 1, 11, 1, 2, 1, 4, 1, 3, 1, 2, 1, 52, 1, 13, 1, 2, 1, 3, 1, 4, 1, 2, 1, 64, 1, 66, 1, 2, 1, 70, 1, 72, 1, 2, 1, 17, 1, 3, 1, 2, 1, 5
OFFSET
1,2
COMMENTS
Conjecture: there is an infinity of numbers n such that a(n)=n.
LINKS
EXAMPLE
n=1 => prime(1)=2 and a(1+2k)=1 => a(1)=a(3)=a(5)=... =1;
n=2 => prime(2)=3 and a(2+3k)=2 => a(2)=a(8)=... =2 (the element a(5) is already in the sequence);
n=3 => prime(3)=5 and a(3+5k)=3 => a(18)=3 (the elements a(n) for n<18 are already in the sequence), a(28)=3, a(48)=3,...
MAPLE
with(numtheory):nn:=500:T:=array(1..nn):
for i from 1 to nn do:
T[i]:=0:
od:
for n from 1 to nn do:
p:=ithprime(n):
for m from n by p to nn do:
if T[m]=0 then T[m]:=n:
else
fi:
od:
od:
print(T):
CROSSREFS
Sequence in context: A276094 A247339 A281071 * A346466 A258409 A060680
KEYWORD
nonn
AUTHOR
Michel Lagneau, Apr 12 2015
STATUS
approved