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A181793 Primitive members of A181792. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 25 20:48 EST 2018. Contains 299656 sequences. (Running on oeis4.)