Idoneal numbers: Difference between revisions
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'''[[wp: |
'''[[wp:Idoneal_number|Idoneal numbers]]''' (also called '''suitable''' numbers or '''convenient''' numbers) are the positive integers '''D''' such that any integer expressible in only one way as '''x<sup>2</sup> ± Dy<sup>2</sup>''' (where '''x<sup>2</sup>''' is relatively prime to '''Dy<sup>2</sup>''') is a prime power or twice a prime power. |
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A positive integer '''n''' is idoneal if and only if it cannot be written as '''ab + bc + ac''' for distinct positive integers '''a''', '''b''', and '''c''' with '''0 < a < b < c'''. |
A positive integer '''n''' is idoneal if and only if it cannot be written as '''ab + bc + ac''' for distinct positive integers '''a''', '''b''', and '''c''' with '''0 < a < b < c'''. |
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;See also |
;See also |
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;* [[wp: |
;* [[wp:Idoneal_number|Wikipedia: Idoneal numbers]] |
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;* [[oeis:A000926|OEIS:A000926 - Euler's "numerus idoneus" (or "numeri idonei", or idoneal, or suitable, or convenient numbers)]] |
;* [[oeis:A000926|OEIS:A000926 - Euler's "numerus idoneus" (or "numeri idonei", or idoneal, or suitable, or convenient numbers)]] |
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