A095167 Triangle read by rows in which the n-th row contains n numbers noncoprime to n and not occurring in earlier rows.

1, 2, 4, 3, 6, 9, 8, 10, 12, 14, 5, 15, 20, 25, 30, 16, 18, 21, 22, 24, 26, 7, 28, 35, 42, 49, 56, 63, 32, 34, 36, 38, 40, 44, 46, 48, 27, 33, 39, 45, 51, 54, 57, 60, 66, 50, 52, 55, 58, 62, 64, 65, 68, 70, 72, 11, 77, 88, 99, 110, 121, 132, 143, 154, 165, 176, 69, 74, 75, 76

Offset

1,2

Comments

Rearrangement of natural numbers so that next n numbers are not coprime to n.

Links

Ivan Neretin, Rows n = 1..141, flattened

Example

1
2 4
3 6 9
8 10 12 14
5 15 20 25 30
16 18 21 22 24 26
7 28 35 42 49 56 63
...

Mathematica

Fold[Function[{a, n}, Join[a, Select[Complement[Range[Max[a] + n^2], a], GCD[n, #] > 1 &, n]]], {1}, Range[2, 12]] (* Ivan Neretin, Jun 05 2015 *)

Prog

(PARI) S=Set(); for(n=2, 20, k=0; m=1; while(k<n, m++; if(!setsearch(S, m)&&gcd(m, n)>1, S=setunion(S, [m]); print1(" ", m); k++))) (Alekseyev)

Crossrefs

Cf. A095168, A095169, A095170, A095171.

Cf. A081964 (coprime instead of non-coprime).

Sequence in context: A075652 A331018 A054428 * A075383 A338919 A348018

Adjacent sequences: A095164 A095165 A095166 * A095168 A095169 A095170

Keyword

nonn,tabl

Author

Amarnath Murthy, Jun 01 2004

Extensions

More terms from Max Alekseyev, Jun 30 2005

Status

approved