A124738 Irregular table where the n-th row consists of those positive integers which are coprime to both n and n+1 and which are <= n.

1, 1, 1, 1, 3, 1, 1, 5, 1, 3, 5, 1, 5, 7, 1, 7, 1, 3, 7, 9, 1, 5, 7, 1, 5, 7, 11, 1, 3, 5, 9, 11, 1, 11, 13, 1, 7, 11, 13, 1, 3, 5, 7, 9, 11, 13, 15, 1, 5, 7, 11, 13, 1, 5, 7, 11, 13, 17, 1, 3, 7, 9, 11, 13, 17, 1, 11, 13, 17, 19, 1, 5, 13, 17, 19, 1, 3, 5, 7, 9, 13, 15, 17, 19, 21, 1, 5, 7, 11, 13

Offset

1,5

Comments

The n-th row has A057475(n) terms.

Links

Table of n, a(n) for n=1..90.

Example

The positive integers which are coprime to 8 and which are <= 8 are 1,3,5,7. The integers which are coprime to 9 and which are <= 9 are 1, The integers in both these sequences (1,5,7) make up the row of A124738.

Mathematica

f[n_] := Select[Range[n], GCD[n, # ] == GCD[n + 1, # ] == 1 &]; Flatten[Table[f[n], {n, 23}]] (* Ray Chandler, Nov 10 2006 *)

Crossrefs

Cf. A057475, A124739, A124740, A124741.

Sequence in context: A329984 A261697 A261698 * A131086 A201669 A069002

Adjacent sequences: A124735 A124736 A124737 * A124739 A124740 A124741

Keyword

nonn,tabf

Author

Leroy Quet, Nov 06 2006

Extensions

Extended by Ray Chandler, Nov 10 2006

Status

approved