A101174 Triangle formed by grouping the natural numbers so that the n-th row contains n numbers whose product has exactly n prime divisors, minimizing (1) final term of row and (2) product of terms of row.

2, 3, 4, 1, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 48, 44, 46, 47, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72

Offset: 1

Author

Ray Chandler, Dec 03 2004

Keywords

• nonn
• tabl

Comments

Variation of A077172.

Examples

			Triangle begins:
2
3,4
1,5,6
7,8,9,10
11,12,13,14,16
15,17,18,19,20,21
22,23,24,25,26,27,28
29,30,31,32,33,34,35,36
37,38,39,40,41,42,43,45,48
44,46,47,49,50,51,52,53,54,55
56,57,58,59,60,61,62,63,64,65,66
67,68,69,70,71,72,73,74,75,76,77,80
78,79,81,82,83,84,85,86,87,88,89,90,91
		

Crossrefs

Cf. A101175, A101176, A101177, A101178, A101179.

Cf. A093451.