

A173540


Triangle read by rows in which row n lists the proper nondivisors of n, or zero if n <= 2.


11



0, 0, 2, 3, 2, 3, 4, 4, 5, 2, 3, 4, 5, 6, 3, 5, 6, 7, 2, 4, 5, 6, 7, 8, 3, 4, 6, 7, 8, 9, 2, 3, 4, 5, 6, 7, 8, 9, 10, 5, 7, 8, 9, 10, 11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 2, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 3, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 2, 3, 4, 5, 6, 7
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OFFSET

1,3


COMMENTS

Define "proper nondivisors of n" as the positive numbers less than n that do not divide n.
Note that a(1) = 0 and a(2) = 0, by convention.
Row sums give A024816.
Row products give A055067, except the first two rows.  Reinhard Zumkeller, Feb 06 2012
T(n,1) = A199968(n).  Reinhard Zumkeller, Oct 02 2015
The nth row has A049820(n) terms.  Michel Marcus, Dec 23 2015


LINKS

Reinhard Zumkeller, Rows n=1..150 of triangle, flattened


EXAMPLE

If written as a triangle:
0;
0;
2;
3;
2, 3, 4;
4, 5;
2, 3, 4, 5, 6;
3, 5, 6, 7;
2, 4, 5, 6, 7, 8;
3, 4, 6, 7, 8, 9;
2, 3, 4, 5, 6, 7, 8, 9, 10;
5, 7, 8, 9, 10, 11;
2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12;
3, 4, 5, 6, 8, 9, 10, 11, 12, 13;
2, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14;
3, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15;


MATHEMATICA

Join[{0, 0}, Flatten[Table[Complement[Range[n], Divisors[n]], {n, 1, 20}]]] (* Geoffrey Critzer, Dec 13 2014 *)


PROG

(Haskell)
a173540 n k = a173540_row n !! (k1)
a173540_row n = a173540_tabf !! (n1)
a173540_tabf = [0] : [0] : map
(\v > [w  w < [2 .. v  1], mod v w > 0]) [3..]
 Reinhard Zumkeller, Oct 02 2015, Feb 06 2012


CROSSREFS

Cf. A027750, A049820, A177235.
Cf. A199968, A024816 (row sums).
Sequence in context: A002372 A035026 A224962 * A070770 A292599 A071487
Adjacent sequences: A173537 A173538 A173539 * A173541 A173542 A173543


KEYWORD

easy,nonn,tabf


AUTHOR

Omar E. Pol, May 24 2010


STATUS

approved



