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 A077011 Triangle in which n-th row contains all possible products of n-1 of the first n primes in ascending order. 4
 1, 2, 3, 6, 10, 15, 30, 42, 70, 105, 210, 330, 462, 770, 1155, 2310, 2730, 4290, 6006, 10010, 15015, 30030, 39270, 46410, 72930, 102102, 170170, 255255, 510510, 570570, 746130, 881790, 1385670, 1939938, 3233230, 4849845, 9699690, 11741730 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A024451(n) gives the sum of the n-th row. When parsed in blocks of ascending length, as shown in the example, there is the following interpretation: The integers Z regarded as a module over themselves contains unshortenable generating sets of different lengths, in fact, infinitely many of each desired length. Each of the blocks is the minimal example of an unshortenable generating set of the respective length. For example, {6,10,15} generates Z as 1=6+10-15. However, removing one of the numbers leaves two numbers that are not relatively prime, precluding generation of Z. An analogous argument succeeds for all other blocks alike. Each block contains numbers such that there is no prime factor common to all. Taking differences sufficiently often one ends up with two coprime numbers whence the generating property follows from Bezout's theorem. Removing just one number from the set, relative primality is lost. The minimality of the numbers used in each block is evident from the construction. - Peter C. Heinig (algorithms(AT)gmx.de), Oct 04 2006 LINKS Alois P. Heinz, Rows n = 1..130, flattened EXAMPLE 1; 2, 3; 6, 10, 15; 30, 42, 70, 105; 210, 330, 462, 770, 1155; 2310, 2730, 4290, 6006, 10010, 15015; 30030, 39270, 46410, 72930, 102102, 170170, 255255; MAPLE T:= proc(n) local t;       t:= mul(ithprime(i), i=1..n);       seq(t/ithprime(n-i), i=0..n-1)     end: seq(T(n), n=1..10);  # Alois P. Heinz, Jun 04 2012 MATHEMATICA T[n_] := Module[{t = Product[Prime[i], {i, 1, n}]}, Table[t/Prime[n - i], {i, 0, n - 1}]]; Table[T[n], {n, 1, 10}] // Flatten (* Jean-François Alcover, May 19 2016, translated from Maple *) CROSSREFS Cf. A024451. Sequence in context: A018141 A178659 A268064 * A246868 A055789 A238891 Adjacent sequences:  A077008 A077009 A077010 * A077012 A077013 A077014 KEYWORD nonn,tabl AUTHOR Amarnath Murthy, Oct 26 2002 EXTENSIONS More terms from Sascha Kurz, Jan 26 2003 STATUS approved

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Last modified September 28 13:24 EDT 2020. Contains 337393 sequences. (Running on oeis4.)