A124822 a(n) = the n-th integer from among those positive integers which are coprime to n(n+1).

1, 5, 7, 9, 17, 19, 15, 23, 31, 27, 35, 37, 31, 59, 53, 33, 53, 55, 49, 83, 79, 49, 71, 89, 67, 83, 95, 67, 109, 113, 63, 103, 113, 103, 151, 109, 79, 127, 157, 101, 145, 149, 95, 179, 173, 97, 143, 167, 141, 197, 175, 113, 161, 223, 173, 199, 185, 121, 223, 227, 127, 223

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

The positive integers which are coprime to (5*6) are 1,7,11,13,17,19,23,29,... The fifth of these integers is 17, so a(5) = 17.

Mathematica

f[n_] := Block[{k = 0, c = n}, While[c > 0, k++; While[GCD[n*(n + 1), k] > 1, k++ ]; c--; ]; k]; Table[f[n], {n, 65}] (* Ray Chandler, Nov 10 2006 *)
Table[Select[Range[n(n+1)], CoprimeQ[#, n(n+1)]&][[n]], {n, 70}] (* Harvey P. Dale, May 01 2016 *)

Crossrefs

Cf. A124823.

Sequence in context: A264747 A294908 A036708 * A072180 A162848 A259359

Adjacent sequences: A124819 A124820 A124821 * A124823 A124824 A124825

Keyword

nonn

Author

Leroy Quet, Nov 08 2006

Extensions

Extended by Ray Chandler, Nov 10 2006

Status

approved