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A261987
Triangle read by rows: row n lists the set of n coprime composite numbers that minimizes the difference between first and last terms, and then minimizes the average of the terms.
4
4, 8, 9, 25, 26, 27, 91, 92, 93, 95, 115, 116, 117, 119, 121, 527, 529, 531, 532, 533, 535, 527, 529, 531, 533, 535, 536, 539, 1331, 1333, 1334, 1337, 1339, 1341, 1343, 1345, 1331, 1333, 1334, 1337, 1339, 1341, 1343, 1345, 1349
OFFSET
1,1
COMMENTS
The minimal set of the (k+n)th row is determined by the minimal k-tuple coprime to the n-th primorial, where every prime <= to the n-th prime must be a factor of some number in the set. E.g., the sixth row must consist of numbers congruent to 5, 7, 11 and 13 mod 6, as well as one term with a factor of 2 and another with a factor of 3.
In cases where multiple k-tuples satisfy the definition, the lexicographically earliest solution is chosen.
LINKS
EXAMPLE
4;
8, 9;
25, 26, 27;
91, 92, 93, 95;
115, 116, 117, 119, 121;
527, 529, 531, 532, 533, 535;
...
CROSSREFS
Subsequence of A002808.
First column is A262042.
Cf. A264482.
Sequence in context: A035326 A180865 A063907 * A158340 A350014 A259183
KEYWORD
tabl,nonn
AUTHOR
Max Barrentine, Oct 02 2015, Nov 03 2015, Nov 05 2015
STATUS
approved