OFFSET
1,1
COMMENTS
Erdős and Pomerance showed in 1978 that this sequence is infinite.
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
Paul Erdős and Carl Pomerance, On the largest prime factors of n and n+1, Aequationes Math. 17 (1978), pp. 311-321.
MATHEMATICA
gpf[n_] := FactorInteger[n][[-1, 1]]; ind = Position[Differences[Array[gpf, 350, 2]], _?(# > 0 &)] // Flatten; ind[[Position[Differences[ind], 1] // Flatten]] + 1 (* Amiram Eldar, Jun 05 2022 *)
PROG
(PARI) for(n=2, 500, if(sign(component(component(factor(n), 1), omega(n))-component(component(factor(n+1), 1), omega(n+1)))+sign(component(component(factor(n+1), 1), omega(n+1))-component(component(factor(n+2), 1), omega(n+2)))==-2, print1(n, ", ")))
(Python)
from sympy import factorint
A071869_list, p, q, r = [], 1, 2, 3
for n in range(2, 10**4):
p, q, r = q, r, max(factorint(n+2))
if p < q < r:
A071869_list.append(n) # Chai Wah Wu, Jul 24 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jun 09 2002
STATUS
approved