

A228122


Smallest nonnegative number x such that x^2 + x + 41 has exactly n prime factors counting multiplicities.


4




OFFSET

1,2


LINKS



EXAMPLE

a(1) = 0 because if x = 0 then x^2 + x + 41 = 41, which has 1 prime factor.
a(2) = 40 because if x = 40 then x^2 + x + 41 = 1681 = 41*41, which has 2 prime factors, counting multiplicities.
a(3) = 420 because if x = 420 then x^2 + x + 41 = 176861 = 47*53*71, which has 3 prime factors.


MATHEMATICA

a = {}; Do[x = 0; While[PrimeOmega[x^2 + x + 41] != k, x++]; AppendTo[a, x], {k, 9}]; a


PROG

(PARI) a(n) = {my(m=0); while (bigomega(m^2+m+41) != n, m++); m; } \\ Michel Marcus, Jan 31 2016
(Python)
from sympy import factorint
k = 0
while sum(factorint(k*(k+1)+41).values()) != n:
k += 1


CROSSREFS



KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



