STATUS
reviewed
approved
The OEIS is supported by the many generous donors to the OEIS Foundation.
reviewed
approved
proposed
reviewed
editing
proposed
(Python)
from itertools import islice
from sympy import divisors
def A253415_gen(): # generator of terms, first term is a(2)
bset, m, s = {1}, 2, 3
while True:
for d in divisors(s):
if d not in bset:
bset.add(d)
while m in bset:
m += 1
yield m
s += d
break
A253415_list = list(islice(A253415_gen(), 30)) # Chai Wah Wu, Jan 25 2022
approved
editing
Michael De Vlieger, <a href="/A253415/b253415_1.txt">Table of n, a(n) for n = 2..10000</a> (terms 2..797 from Reinhard Zumkeller)
proposed
approved
editing
proposed
Reinhard Zumkeller, Michael De Vlieger, <a href="/A253415/b253415_1.txt">Table of n, a(n) for n = 2..10000</a> (terms 2..797</a> from Reinhard Zumkeller)
c[_] = 0; c[1] = j = 1; u = 2; s = 3; Reap[Do[d = Divisors[s]; k = 1; While[c[d[[k]]] > 0, k++]; Set[k, d[[k]]]; Set[c[k], i]; If[k == u, While[c[u] > 0, u++]]; Sow[u]; j = k; s += k, {i, 2, 2^12}]][[-1, -1]] (* Michael De Vlieger, Jan 23 2022 *)
approved
editing
editing
approved
(Haskell)
import Data.List (delete)
a253415 n = a253415_list !! (n-2)
a253415_list = f [2..] 1 where
f xs z = g xs where
g (y:ys) = if mod z' y > 0 then g ys else x : f xs' (z + y)
where xs'@(x:_) = delete y xs
z' = z + 2
-- Reinhard Zumkeller, Dec 31 2014