id:A020669 - OEIS Search Results

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A020669

Numbers of form x^2 + 5 y^2.

+0
7

0, 1, 4, 5, 6, 9, 14, 16, 20, 21, 24, 25, 29, 30, 36, 41, 45, 46, 49, 54, 56, 61, 64, 69, 70, 80, 81, 84, 86, 89, 94, 96, 100, 101, 105, 109, 116, 120, 121, 125, 126, 129, 134, 141, 144, 145, 149, 150, 161, 164, 166, 169, 174, 180, 181, 184, 189, 196, 201, 205, 206, 214, 216 (list; graph; listen)

	OFFSET	`1,3`
	REFERENCES	`H. Cohn, A second course in number theory, John Wiley & Sons, Inc., New York-London, 1962. see page 3.`
	FORMULA	`Numbers represented by quadratic form with Gram matrix [ 1, 0; 0, 5 ].` `List contains 0 and all positive n such that 2*A035170(n)=A028586(2n) is nonzero. - Michael Somos Oct 21 2006`
	CROSSREFS	`Sequence in context: A064931 A073263 A039013 this_sequence A091730 A058076 A033819` `Adjacent sequences: A020666 A020667 A020668 this_sequence A020670 A020671 A020672`
	KEYWORD	`easy,nonn`
	AUTHOR	`David W. Wilson (davidwwilson(AT)comcast.net)`

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Last modified November 23 10:40 EST 2009. Contains 167421 sequences.

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