

A221794


Number of primes of the form (x+1)^3  x^3 with x <= 10^n.


3




OFFSET

0,2


COMMENTS

Cuban primes are primes that are the difference of two consecutive cubes, p = (x+1)^3  x^3 (A002407). They are also primes of the form 3k(k+1) + 1, where values for k+1 are in A002504.


LINKS

Table of n, a(n) for n=0..6.
Ed Pegg, Jr., MathWorld: Cuban Prime
Wikipedia, Cuban prime


CROSSREFS

Cf. A002407, A002504, A003215, A113478 (number of cuban primes < 10^n).
Sequence in context: A127016 A152239 A152240 * A187246 A278152 A271427
Adjacent sequences: A221791 A221792 A221793 * A221795 A221796 A221797


KEYWORD

nonn


AUTHOR

Vladimir Pletser, Jan 25 2013


STATUS

approved



