OFFSET
1,1
COMMENTS
Analogous to A071395 with abundancy index 4 instead of 2.
REFERENCES
Paul Erdős and János Surányi, Topics in the Theory of Numbers, New York: Springer, 2003, p. 243.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Graeme L. Cohen, Primitive alpha-abundant numbers, Mathematics of Computation, Vol. 43, No. 167 (1984), pp. 263-270.
Paul Erdős, On additive arithmetical functions and applications of probability to number theory, Proceedings of the International Congress of Mathematicians, 1954, Amsterdam, Vol. 3 (1956), pp. 13-19.
Paul Erdős, Remarks on number theory. I: On primitive alpha-abundant numbers, Acta Arithmetica., Vol. 5, No. 1 (1959), pp. 25-33, alternative link.
MATHEMATICA
Select[Range@500000, DivisorSigma[1, #] > 4 # && Times @@ Boole@ Map[DivisorSigma[1, #] < 4 # &, Most@ Divisors@ #] == 1 &] (* after Michael De Vlieger at A071395 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Mar 25 2019
STATUS
approved