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 A269065 Irregular triangle read by rows: row n lists divisors of n-th composite number. 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Subsequence of A027750. Row sums give A073255. Right border gives A002808. LINKS Table of n, a(n) for n=1..104. 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 EXAMPLE 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; ... MATHEMATICA Flatten[Table[Divisors[Composite[n]], {n, 22}]] PROG (PARI) tabf(nn) = forcomposite(c=1, nn, print(divisors(c), ", ")); \\ Michel Marcus, Feb 21 2016 CROSSREFS Cf. A002808, A027750, A035004 (row length), A133021, A133031, A138881. Sequence in context: A053450 A352533 A215905 * A206475 A227184 A124911 Adjacent sequences: A269062 A269063 A269064 * A269066 A269067 A269068 KEYWORD nonn,tabf AUTHOR Ilya Gutkovskiy, Feb 21 2016 STATUS approved

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Last modified August 15 04:38 EDT 2024. Contains 375172 sequences. (Running on oeis4.)