A077581 Triangle in which row n contains the n smallest numbers starting from 1 and coprime to n.

1, 1, 3, 1, 2, 4, 1, 3, 5, 7, 1, 2, 3, 4, 6, 1, 5, 7, 11, 13, 17, 1, 2, 3, 4, 5, 6, 8, 1, 3, 5, 7, 9, 11, 13, 15, 1, 2, 4, 5, 7, 8, 10, 11, 13, 1, 3, 7, 9, 11, 13, 17, 19, 21, 23, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 1, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12

Offset

1,3

Comments

A247815 and A247892 give number of primes and nonprimes per row. - Reinhard Zumkeller, Sep 26 2014

Links

Reinhard Zumkeller, Rows n = 1..125 of triangle, flattened

Example

1;
1,  3;
1,  2,  4;
1,  3,  5,  7;
1,  2,  3,  4,  6;
1,  5,  7, 11, 13, 17;
1,  2,  3,  4,  5,  6,  8;
1,  3,  5,  7,  9, ...

Mathematica

row[n_] := Take[Select[Range[n^2], GCD[ #, n]==1&], n]; Join@@row/@Range[13]

Prog

(Haskell)
a077581 n k = a077581_tabl !! (n-1) !! (k-1)
a077581_row n = a077581_tabl !! (n-1)
a077581_tabl = map (\x -> take x [z | z <- [1..], gcd x z == 1]) [1..]
-- Reinhard Zumkeller, Sep 26 2014

Crossrefs

Cf. A069213, A077582.

Cf. A247798 (central terms), A247815, A247892.

Cf. A077664.

Sequence in context: A251621 A016468 A134839 * A130419 A083110 A059016

Adjacent sequences: A077578 A077579 A077580 * A077582 A077583 A077584

Keyword

nonn,tabl,easy,look

Author

Amarnath Murthy, Nov 14 2002

Extensions

More terms from Sascha Kurz, Jan 11 2003

Status

approved