

A077553


Triangle in which the nth row contains n distinct composite numbers with the least product and has least number of prime divisors. No member of a row is a multiple of another member of the row.


4



4, 4, 6, 4, 6, 9, 4, 6, 9, 10, 4, 6, 9, 10, 15, 4, 6, 9, 10, 15, 25, 4, 6, 9, 10, 14, 15, 21, 4, 6, 9, 10, 14, 15, 21, 25, 4, 6, 9, 10, 14, 15, 21, 25, 35, 4, 6, 9, 10, 14, 15, 21, 25, 35, 49, 4, 6, 9, 10, 14, 15, 21, 22, 25, 33, 35, 4, 6, 9, 10, 14, 15, 21, 22, 25, 33, 35, 49, 4, 6, 9, 10
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OFFSET

0,1


COMMENTS

If there are two sets of distinct composite numbers satisfying the above condition then the set with lesser product is chosen irrespective of the number of prime divisors. Perhaps the ambiguity may not arise. E.g., row 6 is 4,6,9,10,15,25. This row cannot be extended to get the next row without bringing in another prime because every number divisible by 2,3 or 5 will be a multiple of one of the previous terms. Hence in row 7, prime 7 has to be brought in and then we get a new set of numbers: 4,6,9,10,14,15,21.


LINKS

Table of n, a(n) for n=0..81.


EXAMPLE

4;
4,6;
4,6,9;
4,6,9,10;
4,6,9,10,15;
4,6,9,10,15,25;
4,6,9,10,14,15,21;


CROSSREFS

Cf. A001358, A005843, A077554, A077555, A087112.
Sequence in context: A064041 A241656 A275161 * A010659 A255014 A131089
Adjacent sequences: A077550 A077551 A077552 * A077554 A077555 A077556


KEYWORD

nonn,tabl,changed


AUTHOR

Amarnath Murthy, Nov 10 2002


EXTENSIONS

More terms from Ray Chandler, Aug 21 2003


STATUS

approved



