A195153 Irregular triangle read by rows in which row n lists numbers d-1 that do not divide n, where d divides n.

2, 3, 4, 5, 6, 3, 7, 2, 8, 4, 9, 10, 5, 11, 12, 6, 13, 2, 4, 14, 3, 7, 15, 16, 5, 8, 17, 18, 3, 9, 19, 2, 6, 20, 10, 21, 22, 5, 7, 11, 23, 4, 24, 12, 25, 2, 8, 26, 3, 6, 13, 27, 28, 4, 9, 14, 29, 30, 3, 7, 15, 31, 2, 10, 32, 16, 33, 4, 6, 34, 5, 8, 11, 17, 35

Offset

3,1

Comments

It appears that only rows 3, 4, 6, 8, 12, 24 have the property that all their members are primes. See the example. See also the comment at A018253.

Links

T. D. Noe, Rows n = 3..1000, flattened

Example

Written as an irregular triangle:
2,
3,
4,
5,
6,
3, 7,
2, 8,
4, 9,
10,
5, 11,
12,
6, 13,
2, 4, 14,
3, 7, 15,
16,
5, 8, 17,
18,
3, 9, 19,
2, 6, 20,
10, 21,
22,
5, 7, 11, 23

Mathematica

Flatten[Table[d = Divisors[n]; Select[Rest[d-1], Mod[n, #] > 0 &], {n, 3 , 100}]] (* T. D. Noe, Sep 23 2011 *)

Crossrefs

Cf. A018253, A027750, A173540, A195150.

Sequence in context: A286450 A245344 A323074 * A328764 A323081 A274630

Adjacent sequences: A195150 A195151 A195152 * A195154 A195155 A195156

Keyword

nonn,tabf

Author

Omar E. Pol, Sep 19 2011

Status

approved