OFFSET
1,4
COMMENTS
The length of row n is A264440(n). - Wolfdieter Lang, Jan 16 2016
Row n lists the nontrivial divisors of n, or 0 if there are no such divisors. - Omar E. Pol, Nov 22 2010
EXAMPLE
From Omar E. Pol, Nov 22 2010: (Start)
The irregular triangle begins:
0;
0;
0;
2;
0;
2, 3;
0;
2, 4;
3;
2, 5;
0,
2, 3, 4, 6;
(End)
MAPLE
for n from 1 to 80 do if isprime(n) or n = 1 then printf("0, ") ; else dvs := sort(convert(numtheory[divisors](n) minus {1, n}, list) ) ; for d in dvs do printf("%d, ", d) ; od: fi ; od: # R. J. Mathar, May 23 2008
with(numtheory): A:=proc (n) local div: div:=divisors(n): `minus`(div, {div[tau(n)], div[1]}) end proc: for n to 35 do A(n) end do: a:=proc (n) if A(n)={} then 0 else seq(A(n)[j], j=1..tau(n)-2) end if end proc: for n to 35 do a(n) end do; # yields sequence in triangular form - Emeric Deutsch, May 25 2008
MATHEMATICA
Array[Complement[Divisors@ #, {1, #}] &, {42}] /. {} -> {0} // Flatten (* Michael De Vlieger, Jan 16 2016 *)
CROSSREFS
KEYWORD
nonn,tabf,easy
AUTHOR
N. J. A. Sloane, May 08 2008
EXTENSIONS
More terms from R. J. Mathar and Emeric Deutsch, May 23 2008
STATUS
approved