A181793 Primitive members of A181792.

28, 52, 76, 124, 148, 172, 175, 244, 268, 292, 316, 325, 388, 412, 436, 475, 508, 556, 604, 628, 652, 724, 772, 775, 796, 844, 847, 892, 916, 925, 964, 1075, 1084, 1108, 1132, 1228, 1252, 1324, 1348, 1396, 1468, 1492, 1516, 1525, 1573, 1588, 1636, 1675, 1684, 1732, 1756, 1825, 1828, 1852, 1948, 1975, 1996

Offset

1,1

Comments

A member of A181792 is called primitive iff it is not a multiple of any smaller member of A181792. Every member of A181792 is a multiple of at least one member of this sequence.

Equivalently, positive integers of the form p*q^2, where p is a prime congruent to 1 mod 3 and q is a prime congruent to 2 mod 6.

Links

Table of n, a(n) for n=1..57.

Example

Of 28's 6 divisors, 4 (1, 4, 7, and 28) are congruent to 1 mod 3; 2 (2 and 14) are congruent to 2 mod 3; and 0 are congruent to 0 mod 3.  Note that 4, 2, and 0 are congruent to 1 mod 3, 2 mod 3, and 0 mod 3 respectively. 28 therefore belongs to A181792.  Since no smaller divisor of 28 belongs to A181792, 28 also belongs to this sequence.

Crossrefs

Subsequence of A054753.

Sequence in context: A039772 A291855 A181792 * A224545 A216303 A261105

Adjacent sequences: A181790 A181791 A181792 * A181794 A181795 A181796

Keyword

nonn

Author

Matthew Vandermast, Nov 13 2010

Status

approved