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A375517
a(n) = A375516(n)/n.
5
2, 2, 4, 12, 240, 40200, 1385211600, 1469089808430082650, 1705264091048404496800363077779646800, 2355419752377504356995163180927294204575594409432081035253034399529376520
OFFSET
1,1
LINKS
EXAMPLE
The prime factors (without repetition) of the first ten terms are:
{2},
{2},
{2},
{2, 3},
{2, 3, 5},
{2, 3, 5, 67},
{2, 3, 5, 67, 5743},
{2, 3, 5, 7, 67, 5743, 1212060151},
{2, 5, 7, 67, 137, 151, 5743, 10867, 1212060151, 5808829669},
{2, 3, 5, 7, 19, 47, 67, 71, 137, 151, 5743, 10867, 1212060151, 5808829669, 243254025696427, 99509446928973841}
MAPLE
s:= proc(n) s(n):= `if`(n=0, 0, s(n-1)+1/(n*b(n))) end:
b:= proc(n) b(n):= 1+floor(1/((1-s(n-1))*n)) end:
a:= n-> denom(s(n))/n:
seq(a(n), n=1..10); # Alois P. Heinz, Oct 19 2024
PROG
(Python)
from itertools import count, islice
from math import gcd
def A375517_gen(): # generator of terms
p, q = 0, 1
for k in count(1):
m = q//(k*(q-p))+1
p, q = p*k*m+q, k*m*q
p //= (r:=gcd(p, q))
q //= r
yield q//k
A375517_list = list(islice(A375517_gen(), 11)) # Chai Wah Wu, Aug 28 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Aug 20 2024
STATUS
approved