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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.
5
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.
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
KEYWORD
nonn,tabf
AUTHOR
Leroy Quet, Nov 06 2006
EXTENSIONS
Extended by Ray Chandler, Nov 10 2006
STATUS
approved