OFFSET
1,2
COMMENTS
Terms greater than 1 are prime.
LINKS
Brian Conrey and Neil Shah, Which numbers are not the sum plus the product of three positive integers?, arXiv:2112.15551 [math.NT], 2021.
PROG
(PARI) isok(n) = sum(x=1, n\3, sum(y=x, (n-x*(1+x^2))\2, (n-x-y)%(x*y+1)==0&&n-x>=y*(x*y+2))) == 0; \\ see A260803
(Python)
from itertools import count, islice
def A350535_gen(startvalue=1): # generator of terms >= startvalue
for n in count(max(startvalue, 1)):
flag = True
for x in range(1, n+1):
if 3*x+x**3 > n or not flag:
break
for y in range(x, n+1):
if x+2*y+x*y**2 > n:
break
if (n-x-y)%(1+x*y) == 0 and x+y*(2+x*y)<= n:
flag = False
break
if flag:
yield n
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Jan 04 2022
STATUS
approved