OFFSET
1,3
COMMENTS
a(n) is the least k such that n - 1 iterations of A004648 (k -> prime(k) (mod k)) are needed to reach 0.
FORMULA
A127064(a(n)) = n.
EXAMPLE
a(6) = 17 because 5 iterations of A004648 starting at 17 result in 0, and every k < 17 requires fewer iterations:
prime(17) (mod 17) = 59 (mod 17) = 8
prime(8) (mod 8) = 19 (mod 8) = 3
prime(3) (mod 3) = 5 (mod 3) = 2
prime(2) (mod 2) = 3 (mod 2) = 1
prime(1) (mod 1) = 2 (mod 1) = 0.
MAPLE
P:= select(isprime, [2, seq(i, i=3..10^8, 2)]): nP:= nops(P):
V:= Array(0..nP): count:= 0: R[1]:= 0:
for n from 1 to nP do
V[n]:= V[P[n] mod n]+1;
if V[n] > count then count:= count+1; R[count]:= n fi;
od:
seq(R[i], i=1..count);
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Nov 25 2024
STATUS
approved