id:A066724 - OEIS Search Results

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a(1) = 1, a(2) = 2; for n > 1, a(n) is the least integer > a(n-1) such that the products a(i)*a(j) for 1 <= i < j <= n are all distinct.

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1, 2, 3, 4, 5, 7, 9, 11, 13, 16, 17, 19, 23, 25, 29, 30, 31, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 73, 79, 81, 83, 84, 89, 97, 101, 103, 107, 109, 113, 121, 127, 128, 131, 137, 139, 149, 151, 154, 157, 163, 167, 169, 173, 179, 180, 181, 191, 193, 197, 199, 211 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`The first 15 terms are the same as A026477; the first 13 terms are the same as A026416.`
	EXAMPLE	`a(7) is not 10 because we already have 10 = 25. Of course all primes appear. a(14) is not 24 because if it was there would be a repeat among the terms a(i)a(j) for 1 <= i < j <= 14, namely 316 = 224.`
	CROSSREFS	`Cf. A000028, A026477, A026416, A050376, A084400.` `Cf. A080431.` `Sequence in context: A000028 A026416 A123193 this_sequence A079851 A089237 A009087` `Adjacent sequences: A066721 A066722 A066723 this_sequence A066725 A066726 A066727`
	KEYWORD	`easy,nonn`
	AUTHOR	`Robert E. Sawyer (rs.1(AT)mindspring.com), Jan 18 2002`

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Last modified November 30 13:13 EST 2009. Contains 167758 sequences.

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