The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A077581 Triangle in which row n contains the n smallest numbers starting from 1 and coprime to n. 12
 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 (list; table; graph; refs; listen; history; text; internal format)
 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 28 01:34 EDT 2024. Contains 372900 sequences. (Running on oeis4.)