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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. 5
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 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Variation of A077172.

LINKS

Table of n, a(n) for n=1..72.

EXAMPLE

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.

Sequence in context: A067003 A277884 A117386 * A050144 A124406 A225650

Adjacent sequences:  A101171 A101172 A101173 * A101175 A101176 A101177

KEYWORD

nonn,tabl

AUTHOR

Ray Chandler, Dec 03 2004

STATUS

approved

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Last modified April 10 15:47 EDT 2021. Contains 342845 sequences. (Running on oeis4.)