A111699 a(1)=1. Skipping over integers occurring earlier in the sequence, count down b(n) (b(n)= number of earlier terms of {a(k)} which are coprime to n) from a(n-1) to get a(n). If this is <= 0, instead count up from a(n-1) b(n) positions (skipping already occurring integers) to get a(n).

1, 2, 4, 3, 8, 7, 13, 9, 16, 10, 22, 19, 31, 25, 11, 24, 42, 35, 6, 23, 40, 28, 53, 43, 5, 33, 58, 44, 73, 63, 20, 49, 75, 52, 14, 39, 86, 65, 21, 54, 100, 88, 30, 64, 17, 61, 115, 96, 38, 71, 113, 85, 142, 121, 78, 36, 98, 56, 132, 114, 177, 148, 105, 60, 125, 97, 174, 141, 83

Offset

1,2

Links

Diana Mecum, Table of n, a(n) for n = 1..900 [From Diana L. Mecum, Aug 04 2008]

Example

The first 6 terms of the sequence can be plotted on the number line as:
1,2,3,4,*,*,7,8,*,*,*,*,*.
Now a(6) is 7. Counting b(7) = 5 (because all earlier terms but the 7 are coprime to 7) down from 7 gets a negative integer. So we instead count up 5 positions, skipping the 8 as we count, to arrive at 13 (which is at the rightmost * of the number line above).

Crossrefs

Sequence in context: A337909 A358523 A365930 * A067179 A318993 A355482

Adjacent sequences: A111696 A111697 A111698 * A111700 A111701 A111702

Keyword

nonn

Author

Leroy Quet, Nov 17 2005

Extensions

More terms from Diana L. Mecum, Aug 04 2008

Status

approved