

A095167


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


7



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
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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 noncoprime).
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



