OFFSET
1,1
COMMENTS
Prime factors are counted with multiplicity, as in A144255.
Iwaniec shows that the sequence is infinite.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
H. Iwaniec, Almost-primes represented by quadratic polynomials, Inventiones Mathematicae 47:2 (1978), pp. 171-188.
Vishaal Kapoor, Almost-primes represented by quadratic polynomials, MS thesis (2006). arXiv:1910.02885 [math.NT]
Robert J. Lemke Oliver, Almost-primes represented by quadratic polynomials, Acta Arithm. 151 (2012) 241. DOI: 10.4064/aa151-3-2
Wikipedia, Landau's problems
PROG
(PARI) is(n)=issquare(n-1) && bigomega(n)<3 \\ Charles R Greathouse IV, Feb 05 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
R. J. Mathar, Oct 13 2014
STATUS
approved