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Search: id:A139544
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| A139544 |
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Numbers which are not the difference of two squares of positive integers. |
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+0
2
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| 1, 2, 4, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74, 78, 82, 86, 90, 94, 98, 102, 106, 110, 114, 118, 122, 126, 130, 134, 138, 142, 146, 150, 154, 158, 162, 166, 170, 174, 178, 182, 186, 190, 194, 198, 202, 206, 210, 214, 218, 222, 226, 230
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Conjecture: these numbers do not occur in A139491.
Complement sequence to A024352.
All odd numbers 2k+1 for k>0 can be represented by (k+1)^2-k^2. All multiples 4k for k>1 can be represented by (k+1)^2-(k-1)^2. No number of the form 4k+2 is the difference of two squares because, modulo 4, the differences of two squares are 0, 1, or 3. [From T. D. Noe (noe(AT)sspectra.com), Apr 27 2009]
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CROSSREFS
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Cf. A024352.
Sequence in context: A005574 A109807 A125964 this_sequence A062091 A100143 A059254
Adjacent sequences: A139541 A139542 A139543 this_sequence A139545 A139546 A139547
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Apr 25 2008
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EXTENSIONS
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Corrected by T. D. Noe (noe(AT)sspectra.com), Apr 27 2009
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