A269065 Irregular triangle read by rows: row n lists divisors of n-th composite number.
1, 2, 4, 1, 2, 3, 6, 1, 2, 4, 8, 1, 3, 9, 1, 2, 5, 10, 1, 2, 3, 4, 6, 12, 1, 2, 7, 14, 1, 3, 5, 15, 1, 2, 4, 8, 16, 1, 2, 3, 6, 9, 18, 1, 2, 4, 5, 10, 20, 1, 3, 7, 21, 1, 2, 11, 22, 1, 2, 3, 4, 6, 8, 12, 24, 1, 5, 25, 1, 2, 13, 26, 1, 3, 9, 27, 1, 2, 4, 7, 14, 28, 1, 2, 3, 5, 6, 10, 15, 30, 1, 2, 4, 8, 16, 32, 1, 3, 11, 33, 1, 2, 17, 34
Offset: 1
Examples
Triangle begins: 1, 2, 4; 1, 2, 3, 6; 1, 2, 4, 8; 1, 3, 9; 1, 2, 5, 10; 1, 2, 3, 4, 6, 12; 1, 2, 7, 14; 1, 3, 5, 15 1, 2, 4, 8, 16; 1, 2, 3, 6, 9, 18; 1, 2, 4, 5, 10, 20; 1, 3, 7, 21; 1, 2, 11, 22; 1, 2, 3, 4, 6, 8, 12, 24; 1, 5, 25; 1, 2, 13, 26; 1, 3, 9, 27; 1, 2, 4, 7, 14, 28; 1, 2, 3, 5, 6, 10, 15, 30; 1, 2, 4, 8, 16, 32; 1, 3, 11, 33; 1, 2, 17, 34; ...
Links
- Ilya Gutkovskiy, Extended example
- Ilya Gutkovskiy, Graphic additions
- Eric Weisstein's World of Mathematics, Composite Number
- Eric Weisstein's World of Mathematics, Divisor
- Index entries for sequences related to divisors of numbers
Programs
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Mathematica
Flatten[Table[Divisors[Composite[n]], {n, 22}]] -
PARI
tabf(nn) = forcomposite(c=1, nn, print(divisors(c), ", ")); \\ Michel Marcus, Feb 21 2016
Comments